JP6058473B2 - Lighting power control circuit, semiconductor integrated circuit, lighting power supply and lighting fixture - Google Patents

Description

  The present invention relates to a lighting power supply control circuit, a semiconductor integrated circuit, a lighting power supply, and a lighting fixture. More specifically, in the present invention, an illumination power supply control circuit for controlling an illumination power supply for supplying current to a light emitting module having a current injection type light emitting element, and the illumination power supply control circuit are formed on a semiconductor substrate. The present invention relates to a semiconductor integrated circuit, an illumination power source including the illumination power source control circuit, and a lighting fixture including the illumination power source.

  For lighting fixtures, various regulations (class C at rated output of 25 W or more) are imposed by standards such as IEC and JIS in order to suppress harmonic current. For this reason, the power supply device applied to a lighting fixture is usually provided with a power factor correction circuit such as a boost chopper circuit.

  By the way, in the case of a lighting fixture having a light emitting module using a current injection type light emitting element such as a light emitting diode (LED), the dimming is controlled to a much smaller illuminance (dimming degree) than a conventional discharge lamp by dimming control. Is possible. When the illuminance is low (in the case of deep dimming), the power supply device (illumination power supply) of the lighting fixture needs to supply a much smaller current to the light emitting module than a conventional discharge lamp or the like.

  Note that Patent Document 1 describes a power supply device that suppresses abnormal boosting of the output voltage of a chopper circuit in an operation mode in which power consumption is smaller than that during normal operation. Patent Document 2 describes a power supply device that reduces switching loss in a light load state.

JP 2004-208357 A JP2011-229255A

  As described above, in the case of deep dimming, that is, when the load of the illumination power source is light, the illumination power source needs to supply a much smaller current to the light emitting module than a conventional discharge lamp or the like.

  However, at the time of deep dimming, the ON width of the switch element of the power factor correction circuit is minimized, and when the dimming degree is further lowered, the ON width cannot be further reduced. In such a case, the current flowing through the choke coil of the power factor correction circuit cannot be further reduced. As a result, the output voltage of the power factor correction circuit increases and the overvoltage protection function is activated, thereby causing a problem that the power factor is decreased.

  Here, the above problem will be described in detail with reference to FIG. The upper part of FIG. 8 shows an input AC voltage waveform (for one cycle) of an AC power source such as a commercial power source. The middle part of FIG. 8 shows PFC operation waveforms (IL, Iin) when the power factor correction circuit outputs a rated voltage. The lower part of FIG. 8 shows the PFC operation waveforms (IL, Iin) during deep dimming. In the middle and lower stages of FIG. 8, IL indicates an inductor current flowing through the choke coil of the power factor correction circuit, and Iin is an input current flowing into a smoothing capacitor provided in a rectifier circuit that rectifies the input AC voltage.

  As shown in the middle part of FIG. 8, the power factor correction circuit is current critically controlled at the rated output. That is, when the inductor current IL decreases to zero, the switch element that controls the inductor current becomes conductive, and the inductor current IL increases again. Under current critical control, the input current Iin is almost similar to the waveform of the input AC voltage, and the power factor is improved.

  On the other hand, as shown in the lower part of FIG. 8, at the time of deep dimming, the inductor current IL has a period in which it becomes zero for a while during the current critical control. As described above, this is because the output voltage of the power factor correction circuit is higher than the rated voltage.

  That is, when the output voltage of the power factor correction circuit reaches an abnormal threshold voltage higher than the rated output voltage, the overvoltage protection function is activated and the switching operation of the switch element is forcibly stopped. Here, the overvoltage protection function is provided to prevent the illumination power source from being destroyed due to the output voltage of the power factor correction circuit exceeding the withstand voltage of the smoothing capacitor.

  After the overvoltage protection function is activated, when the output voltage of the power factor correction circuit decreases due to the stop of the switching operation, the prohibition of the switching operation by the overvoltage protection function is released, and the switch element resumes the switching operation.

  However, as shown in the lower part of FIG. 8, the harmonic component of the input current Iin increases due to the stop and restart of the switching operation, and the power factor decreases.

  The present invention has been made based on the above technical recognition, and is a lighting power supply control circuit, a semiconductor integrated circuit, a lighting power supply, and a lighting fixture capable of preventing a reduction in power factor during deep light control. The purpose is to provide.

A lighting power supply control circuit according to one embodiment of the present invention includes:
A rectifier circuit that rectifies and smoothes an input AC voltage output from an AC power supply and outputs an input rectified voltage; an inductor; and a switch element that controls an inductor current flowing through the inductor; and the input rectification by a switching operation of the switch element. A power factor improvement circuit that converts a voltage into a DC voltage, and a DC-DC converter that outputs a DC current based on the DC voltage to a light emitting module having a current injection type light emitting element. Power supply control circuit,
When the dimming degree of the light emitting module set by the dimmer is equal to or higher than a predetermined switching threshold value, current critical control is performed to control the switch element to a conductive state when the inductor current becomes zero,
When the dimming degree is less than the switching threshold, the switch element is turned on at a predetermined turn-on cycle so that the number of turn-on times of the switch element per cycle of the input AC voltage is less than the number of turn-on times in the current critical mode. To perform fixed frequency control to control the conduction state with
It is characterized by that.

In the illumination power supply control circuit,
When the dimming degree is less than the switching threshold and the DC voltage is less than the voltage at which the overvoltage protection function operates, the current critical control may be performed instead of the fixed frequency control.

In the illumination power supply control circuit,
The turn-on period may be set such that the switching frequency of the switch element in the fixed frequency control is higher than the upper limit frequency of the audible region.

In the illumination power supply control circuit,
The turn-on period may be continuously increased as the dimming degree is lowered.

In the illumination power supply control circuit,
You may make it control the said DC-DC converter so that the said DC-DC converter may output the direct current according to the light control degree of the said light emitting module to the said light emitting module.

In the illumination power supply control circuit,
The light emitting element may be a light emitting diode, a laser diode, an organic EL element, or other semiconductor light emitting element.

In the illumination power supply control circuit,
A dimming signal output unit for outputting a dimming signal when the dimming voltage based on the dimming degree of the dimmer is less than a dimming reference voltage corresponding to the switching threshold;
A PFC control unit that performs the fixed frequency control when the depth dimming signal is received, and performs the current critical control when the depth dimming signal is not received;
You may make it provide.

In the illumination power supply control circuit,
The PFC control unit
A timer unit that outputs a first on-trigger signal every turn-on period while receiving the deep dimming signal;
A zero-cross detector that outputs a second on-trigger signal when detecting that the inductor current has become zero;
A signal gate section that passes the second on-trigger signal when not receiving the deep dimming signal, and that does not pass the second on-trigger signal when receiving the deep dimming signal;
A switch current determination unit that outputs a first off-trigger signal when a voltage based on a current flowing through the switch element exceeds a turn-off threshold voltage based on a product of the input rectified voltage and the DC voltage;
An overvoltage detector that outputs a second off-trigger signal when the DC voltage exceeds an abnormal threshold voltage that is higher than the rated output voltage of the power factor correction circuit;
When the first on-trigger signal is received from the timer unit or when the second on-trigger signal is received from the signal gate unit, an on signal for turning on the switch element is output, and the switch current A gate signal output unit that outputs an off signal that turns off the switch element when the first off trigger signal is received from the determination unit or the second off trigger signal is received from the overvoltage detection unit; ,
You may make it have.

In the illumination power supply control circuit,
The timer unit is
A constant current source;
The first on-trigger signal when the voltage of the first input terminal, the second input terminal connected to a predetermined reference voltage, and the voltage of the first input terminal are larger than the voltage of the second input terminal A comparator having an output terminal for outputting
One end is connected to the output terminal of the constant current source, the other end is connected to the first input terminal of the comparator, a gate terminal is connected to the output terminal of the depth dimming signal output unit, and the gate terminal A switch element for supplying current that becomes conductive when receiving the deep dimming signal;
A capacitor having one end connected to the other end of the current supply switch element and the other end grounded;
One end is connected to one end of the capacitor, the other end is grounded, and the discharging switch element that becomes conductive when the gate signal output unit outputs the ON signal;
You may make it have.

In the illumination power supply control circuit,
The timer unit is
A constant current source;
The first on-trigger signal when the voltage of the first input terminal, the second input terminal connected to a predetermined reference voltage, and the voltage of the first input terminal are larger than the voltage of the second input terminal A comparator having an output terminal for outputting
A capacitor having one end connected to the output terminal of the constant current source and the first input terminal of the comparator, and the other end grounded;
One end is connected to one end of the capacitor, the other end is grounded, and the discharging switch element that becomes conductive when the gate signal output unit outputs the ON signal;
You may make it have.

In the illumination power supply control circuit,
A dimming signal output unit for outputting a dimming signal when the dimming voltage based on the dimming degree of the dimmer is less than a dimming reference voltage corresponding to the switching threshold;
When the depth dimming signal is received and the DC voltage is higher than a warning threshold voltage between a rated output voltage of the power factor correction circuit and an abnormal threshold voltage at which an overvoltage protection function operates, the fixed frequency A PFC control unit that performs control, and otherwise performs the current critical control;
You may make it provide.
In the illumination power supply control circuit,
The PFC control unit
When the DC voltage is higher than the warning threshold voltage, an output voltage monitoring unit that outputs an output voltage increase signal;
A first signal gate that passes the depth dimming signal when receiving the output voltage rise signal, and does not pass the depth dimming signal when the output voltage rise signal is not received;
A timer unit that outputs a first on-trigger signal for each turn-on period while receiving the deep dimming signal from the first signal gate unit;
A zero-cross detector that outputs a second on-trigger signal when detecting that the inductor current has become zero;
When the depth dimming signal is not received from the first signal gate unit, the second on-trigger signal is passed, and when the depth dimming signal is received from the first signal gate unit. A second signal gate portion that does not pass the second on-trigger signal;
A switch current determination unit that outputs a first off-trigger signal when a voltage based on a current flowing through the switch element exceeds a turn-off threshold voltage based on a product of the input rectified voltage and the DC voltage;
An overvoltage detector that outputs a second off-trigger signal when the DC voltage exceeds the abnormal threshold voltage;
When the first on-trigger signal is received from the timer unit or when the second on-trigger signal is received from the second signal gate unit, an on signal for turning on the switch element is output, When receiving the first off-trigger signal from the switch current determination unit or when receiving the second off-trigger signal from the overvoltage detection unit, a gate signal that outputs an off signal that turns off the switch element An output section;
You may make it have.

  A semiconductor integrated circuit according to one embodiment of the present invention is characterized in that the illumination power supply control circuit of the present invention is formed over a predetermined semiconductor substrate.

A lighting power source according to one embodiment of the present invention includes:
A rectifying circuit that rectifies and smoothes the input AC voltage output from the AC power supply and outputs the input rectified voltage;
A power factor improving circuit that includes an inductor and a switching element that controls an inductor current flowing through the inductor, and converts the input rectified voltage into a DC voltage by a switching operation of the switching element;
A DC-DC converter that outputs a direct current based on the direct current voltage to a light emitting module having a current injection type light emitting element;
When the dimming degree of the light emitting module set by the dimmer is equal to or greater than a predetermined switching threshold, current critical control is performed to control the switch element to a conductive state when the inductor current becomes zero, When the dimming degree is less than the switching threshold, the switch element is turned on at a predetermined turn-on period so that the turn-on number of the switch element per period of the input AC voltage is less than the turn-on number in the current critical mode. A power supply control circuit for lighting that performs fixed frequency control for forcibly controlling to a conductive state;
It is characterized by providing.

A lighting apparatus according to one embodiment of the present invention includes:
A light emitting module having a current injection type light emitting element;
A rectifying circuit that rectifies and smoothes the input AC voltage output from the AC power supply and outputs the input rectified voltage;
A power factor improving circuit that includes an inductor and a switching element that controls an inductor current flowing through the inductor, and converts the input rectified voltage into a DC voltage by a switching operation of the switching element;
A DC-DC converter that outputs a direct current based on the direct current voltage to the light emitting module;
When the dimming degree of the light emitting module set by the dimmer is equal to or greater than a predetermined switching threshold, current critical control is performed to control the switch element to a conductive state when the inductor current becomes zero, When the dimming degree is less than the switching threshold, the switch element is turned on at a predetermined turn-on period so that the turn-on number of the switch element per period of the input AC voltage is less than the turn-on number in the current critical mode. A power supply control circuit for lighting that performs fixed frequency control for forcibly controlling to a conductive state;
It is characterized by providing.

  In the present invention, when the dimming degree is less than a predetermined switching threshold, the switch element is turned on at a predetermined turn-on time so that the number of turn-on times of the switch element per cycle of the input AC voltage is smaller than the turn-on number in the current critical mode. Fixed frequency control is performed to control the conduction state forcibly in a cycle.

  As a result, an off period of the inductor current occurs, and an increase in the output voltage of the power factor correction circuit is suppressed, so that it is possible to avoid that the switch element is forcibly controlled to be cut off by the overvoltage protection function.

  Therefore, according to the present invention, it is possible to avoid the switching operation of the switch element from being stopped / restarted during the deep dimming, and to prevent the harmonic component of the input current from being generated or increased. As described above, according to the present invention, it is possible to prevent the power factor from being lowered during the deep light control.

It is a schematic block diagram of the lighting fixture which concerns on one embodiment of this invention. It is a circuit diagram of the light control signal input part, the deep light control signal output part, and the PFC control part in the power supply control circuit for illumination which concerns on the 1st embodiment of this invention. It is a circuit diagram centering on the timer part of the power supply control circuit for illumination which concerns on 1st Embodiment. It is a circuit diagram of the PFC control part in the power supply control circuit for illumination which concerns on the modification of 1st Embodiment. FIG. 6 is a waveform diagram of an input AC voltage, a rated PFC operation waveform, and a PFC operation waveform during deep dimming when the illumination power supply control circuit according to the first embodiment is used. It is a circuit diagram of the PFC control part of the power supply control circuit for illumination which concerns on the 2nd Embodiment of this invention. It is a circuit diagram of the PFC control part in the power supply control circuit for illumination which concerns on the modification of a 2nd embodiment. It is a wave form diagram of an input AC voltage, a PFC operation waveform at the time of rating, and a PFC operation waveform at the time of depth dimming when a conventional power supply control circuit for illumination is used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, unless otherwise specified, components having equivalent functions are denoted by the same reference numerals, and detailed description of components having the same reference numerals is not repeated.

(First embodiment)
First, with reference to FIG. 1, the lighting fixture 1 which concerns on the embodiment of this invention is demonstrated. The luminaire 1 is a luminaire that includes a light emitting module 6 having a current injection type light emitting element 7 as an illumination light source, and is capable of adjusting the illuminance (dimming degree) of the light emitting module 6 by a dimmer 8.

  As shown in FIG. 1, the luminaire 1 includes a rectifier circuit 3 connected to an AC power source 2, a power factor correction circuit 4, a DC-DC converter 5, a light emitting module 6 having a light emitting element 7, and dimming. A lighting device 8, a dimming signal receiver 9, and a lighting power supply control circuit 10 are provided. The illumination power supply includes a rectifier circuit 3, a power factor correction circuit 4, a DC-DC converter 5, and an illumination power supply control circuit 10.

  Hereinafter, each component of the lighting fixture 1 is demonstrated in detail.

  The rectifier circuit 3 rectifies and smoothes the input AC voltage output from the AC power source 2 such as a commercial power source, and outputs the rectified and smoothed input rectified voltage to the power factor correction circuit 4. As shown in FIG. 1, the rectifier circuit 3 includes, for example, a diode bridge and a capacitor C1. The diode bridge is composed of four diodes (D1, D2, D3, D4), and full-wave rectifies the input AC voltage of the AC power supply 2. The capacitor C1 is provided to absorb high-frequency ripple current generated in the power factor correction circuit 4, and one end is connected to the output terminal of the diode bridge and the other end is grounded.

  The power factor correction circuit 4 is a circuit that suppresses harmonic components of the input current (Iin) flowing into the capacitor C2 and improves the power factor. The power factor correction circuit 4 includes an inductor (choke coil) L1 and a switch element Q1 that controls a current flowing through the inductor L1 (hereinafter also referred to as “inductor current”). By the switching operation of the switch element Q1, The input rectified voltage is converted into a predetermined DC voltage.

  As shown in FIG. 1, the power factor correction circuit 4 includes, for example, an inductor L1, a switch element Q1, a regeneration diode D5, a smoothing capacitor C2, a monitor winding L2, and resistors R3 and R4. , R5 and a step-up chopper circuit.

  The inductor L1 has one end connected to the output terminal of the rectifier circuit 3, and the other end connected to one end of the switch element Q1 and the anode of the diode D5.

  The switch element Q1 is a transistor (for example, NMOSFET) that is controlled to be in a conductive state or a cutoff state by a gate signal output from the GD terminal of the illumination power supply control circuit 10. One end (drain) of the switch element Q1 is connected to the other end of the inductor L1, and the other end (source) is grounded via a resistor R3.

  The resistor R3 is a resistor for monitoring the current flowing through the switch element Q1. One end of the resistor R3 is connected to the other end (source) of the switch element Q1, and the other end of the resistor R3 is grounded.

  The diode D5 has an anode connected to the other end of the inductor L1, and a cathode connected to the output terminal of the power factor correction circuit 4 (one end of the capacitor C2).

  The resistors R4 and R5 constitute a voltage dividing circuit for monitoring the DC voltage output from the power factor correction circuit 4. One end of the resistor R4 is connected to one end of the capacitor C2, and the other end is connected to one end of the resistor R5. One end of the resistor R5 is connected to the other end of the resistor R4, and the other end is grounded.

  One end of the capacitor C2 is connected to the output terminal of the power factor correction circuit 4, and the other end is grounded.

  The monitoring winding L2 is a winding for monitoring the inductor current flowing through the inductor L1, and has one end grounded and the other end connected to the ZCD terminal of the illumination power supply control circuit 10.

  The power factor correction circuit 4 is configured, for example, as a boost chopper circuit having the above-described configuration, boosts the input rectified voltage to a predetermined voltage, and outputs it to the DC-DC converter 5. Note that the power factor correction circuit 4 is not limited to the above configuration, and other known configurations may be used.

  As shown in FIG. 1, a voltage dividing circuit for monitoring the input rectified voltage is provided between the rectifier circuit 3 and the power factor correction circuit 4. This voltage dividing circuit includes a resistor R1 and a resistor R2 connected in series. One end of the resistor R1 is connected to the output terminal of the rectifier circuit 3, and the other end is connected to one end of the resistor R2. One end of the resistor R2 is connected to the other end of the resistor R1, and the other end is grounded.

  The DC-DC converter 5 receives a DC voltage output from the PFC control circuit 4 and outputs a DC current based on the DC voltage to the light emitting module 6. The direct current output from the DC-DC converter 5 decreases as the dimming degree of the light emitting module 6 decreases.

  As shown in FIG. 1, the DC-DC converter 5 includes, for example, a high-side switch element Q2, a low-side switch element Q3, a step-down diode D6, diodes D7 and D8, a primary winding L3, and a secondary The step-down chopper circuit includes a transformer T having a winding L4, capacitors C3 and C4, and a smoothing capacitor C5.

  The high-side switch element Q2 is a transistor (for example, NMOSFET) that is controlled to be in a conductive state or a cut-off state by a gate signal output from the HO terminal of the illumination power supply control circuit 10. The high side switch element Q2 has one end (drain) connected to the output terminal of the power factor correction circuit 4 and the other end (source) connected to one end (drain) of the low side switch element Q3.

  The low-side switch element Q3 is a transistor (for example, NMOSFET) that is controlled to be in a conductive state or a cut-off state by a gate signal output from the LO terminal of the illumination power supply control circuit 10. The low side switch element Q3 has one end (drain) connected to the other end (source) of the high side switch element Q2 and the other end (source) grounded.

  The step-down diode D6 has a cathode connected to a connection point between the high-side switch element Q2 and the low-side switch element Q3, and an anode grounded.

  The primary winding L3 of the transformer T has one end connected to a connection point between the high-side switch element Q2 and the low-side switch element Q3, and the other end connected to the output terminal of the DC-DC converter 5 (one end of the capacitor C5). Yes. One end of the secondary winding L4 of the transformer T is grounded. This secondary winding L4 constitutes a transformer T together with the primary winding L3.

  One end of the capacitor C3 is connected to a connection point between the high-side switch element Q2 and the low-side switch element Q3, and the other end is grounded to the cathode of the diode D7 and the VB terminal of the illumination power supply control circuit 10. The diode D8 has an anode connected to the other end of the secondary winding L4 and a cathode connected to the Vcc terminal of the illumination power supply control circuit 10.

  The diode D7 has a cathode connected to the other end of the capacitor C3 and an anode connected to the cathode of the diode D8. The control power supply voltage Vcc is supplied from the illumination power supply control circuit 10 to the anode of the diode D7 when the DC-DC converter 5 is started. When switch element Q3 is turned on by this control power supply voltage Vcc, capacitor C3 is charged and a high-side drive voltage is generated.

  Capacitor C4 has one end connected to the cathode of diode D8 and the other end connected to one end of secondary winding L4. The capacitor C5 is connected between the output terminal of the DC-DC converter 5 and the ground.

  The DC-DC converter 5 having the above-described configuration steps down the DC voltage output from the power factor correction circuit 4 to a predetermined DC voltage and supplies a DC current corresponding to the dimming degree to the light emitting module 6. Note that the DC-DC converter 5 is not limited to the step-down chopper circuit having the above-described configuration, and may have another known configuration. Further, the DC-DC converter 5 may be a step-up DC-DC converter according to a desired output voltage.

  Next, the light emitting module 6 will be described. The light emitting module 6 includes a plurality of light emitting element lines 6a and 6b as shown in FIG. Each of the light emitting element lines 6a and 6b has a plurality of light emitting elements 7 connected in series. In addition, each of the light emitting element lines 6a and 6b has one end connected to the output terminal of the DC-DC converter 5 and the other end grounded via a resistor R6. The other ends of the light emitting element lines 6 a and 6 b are also connected to a feedback terminal of the illumination power supply control circuit 10.

  In FIG. 1, the number of light emitting element lines is two. However, the number is not limited to this, and may be one or three or more. Further, the number of light emitting elements 7 included in one light emitting element line is three in FIG. 1, but is not limited thereto.

  The light emitting element 7 is a current injection type light emitting element, for example, a light emitting diode (LED), a laser diode (LD), or an organic EL element. The light emitting element 7 is not limited to this as long as it is a current injection type light emitting element, and may be another semiconductor light emitting element.

  The dimmer 8 is provided on the lighting fixture 1 itself or on the wall of the room. The dimmer 8 has setting means (not shown) such as a knob unit that allows the user to set the dimming degree, and outputs a dimming degree signal corresponding to the set dimming degree (illuminance). This dimming degree signal is, for example, a PWM signal in which the on-duty increases as the set dimming degree decreases.

  The dimming degree signal receiving unit 9 receives the PWM signal output from the dimmer 8, and outputs a PWM signal based on the PWM signal to the DIM-IN terminal of the illumination power supply control circuit 10. As shown in FIG. 1, the dimming signal receiver 9 includes, for example, a photocoupler PC1 having a light emitting diode P1 and a phototransistor P2, and a resistor R7 connected in series to the photocoupler PC1. The voltage output from the dimmer 8 is applied to both ends of the light emitting diode P1. The phototransistor P2 and the resistor R7 are connected in series between the voltage VDD and the ground. The connection point between the phototransistor P2 and the resistor R7 is connected to the DIM-IN terminal of the illumination power supply control circuit 10.

  With such a configuration, the dimming degree signal receiving unit 9 outputs a PWM signal obtained by inverting the PWM signal output from the dimmer 8 to the DIM-IN terminal of the illumination power supply control circuit 10.

  The illumination power supply control circuit 10 is a control circuit that controls the power factor correction circuit 4 and the DC-DC converter 5. As shown in FIG. 1, the illumination power control circuit 10 is connected to the dimmer 8 via the dimming signal receiver 9, and based on the dimming degree set by the dimmer 8, the power factor correction circuit 4. Control. The illumination power supply control circuit 10 controls the DC-DC converter 5 so as to supply a direct current corresponding to the dimming degree by monitoring the current flowing through the light emitting element lines 6a and 6b via the FB terminal. .

  As shown in FIG. 1, the illumination power supply control circuit 10 includes a dimming degree signal input unit 11, a deep dimming signal output unit 12, and a PFC control unit 13, and controls the power factor improvement circuit 4. . In addition, the illumination power supply control circuit 10 includes a dimming output unit 14, an oscillator 15, an operational amplifier 16, a comparator 17, a control unit 18, a switch control unit 19, a soft start unit 20, and a stop unit. 21, a startup power supply unit 22, and a malfunction prevention unit 23.

  The illumination power supply control circuit 10 may be configured as a semiconductor integrated circuit formed on a predetermined semiconductor substrate. That is, some or all of the above-described components of the illumination power supply control circuit 10 may be integrated on a predetermined semiconductor substrate.

  Before describing the control of the power factor correction circuit 4 by the illumination power supply control circuit 10 in detail, the control of the DC-DC converter 5 by the illumination power supply control circuit 10 will be described.

<Control of DC-DC Converter 5 by Lighting Power Supply Control Circuit 10>
Hereinafter, components of the illumination power supply control circuit 10 related to the control of the DC-DC converter 5 will be described.

  The dimming signal input unit 11 inverts the PWM signal received from the DIM-IN terminal, adjusts the ON voltage, and outputs the adjusted signal. A configuration example of the dimming degree signal input unit 11 will be described later with reference to FIG. 2 in the description of the control of the power factor correction circuit 4 by the illumination power supply control circuit 10.

  The dimming output unit 14 adjusts the level of the voltage of the DC-OUT terminal and outputs the voltage to the DIM-OUT terminal. A capacitor C6 is connected to the DC-OUT terminal. The voltage (dimming voltage) at the DC-OUT terminal is a DC voltage obtained by converting the PWM signal output from the dimming signal input unit 11 into a direct current using the capacitor C6, and increases as the dimming level increases.

  The oscillator 15 outputs an oscillation signal (for example, a triangular wave) generated based on the capacitor C8 connected to the CT terminal and the resistor R11 connected to the RT terminal to the comparator 17.

  The operational amplifier 16 has an inverting input terminal (−) connected to the output terminal of the dimming output unit 14 via the resistors Ra and Rc, and a non-inverting input terminal (+) connected to the light emitting element lines 6a and 6b via the resistor Rd. It is connected to the. The resistor Ra has one end connected to the DIM-OUT terminal and the other end connected to one end of the resistor Rb. The other end of the resistor Rb is grounded.

  Further, the inverting input terminal (−) of the operational amplifier 16 is connected to the output terminal of the operational amplifier 16 through the resistors Rc and Re, Rf. The resistor Re has one end connected to the output terminal of the operational amplifier 16 and the other end connected to one end of the resistor Rf. The other end of the resistor Rf is connected to one end of the resistor Rc.

  With such a configuration, the operational amplifier 16 amplifies and outputs the difference between the voltage obtained by dividing the voltage output from the dimming output unit 14 and the voltage based on the current flowing through the light emitting element lines 6a and 6b.

  The comparator 17 compares the oscillation signal output from the oscillator 15 with the signal output from the operational amplifier, and outputs a comparison signal corresponding to the comparison result.

  Based on the comparison signal output from the comparator 17, the control unit 18 drives the high-side switch element Q2 and the low-side switch element Q3 by the switch control unit 19 so that the current flowing through the light-emitting element 7 becomes a target current value. Control. Here, the target current value is a current value corresponding to the dimming degree set by the dimmer 8.

  For example, when the control unit 18 determines that the current flowing through the light emitting element 7 is less than the target current value based on the comparison signal, the on-duty of the high-side switch element Q3 is increased and the on-duty of the low-side switch element Q3 is Control to make it smaller. On the other hand, when it is determined that the current flowing through the light emitting element 7 is equal to or greater than the target current value based on the comparison signal, the control unit 18 reduces the on-duty of the high-side switch element Q2 and the on-duty of the low-side switch element Q3. Control to increase.

  The switch control unit 19 outputs gate signals for driving the high-side switch element Q2 and the low-side switch element Q3 from the HO terminal and the LO terminal, respectively. Thereby, the switch control unit 19 controls the low-side switch element Q2 and the high-side switch element Q3, and drives the DC-DC converter 5 so as to obtain a desired output.

  The soft start unit 20 is configured so that the DC-DC converter 5 is soft-started when the DC-DC converter 5 is started, that is, the output voltage of the DC-DC converter 5 is gradually increased. A signal for controlling the on-duty of the switch element Q3 is output to the control unit 18. In addition, the soft start part 20 is connected to the capacitor | condenser C7 via SS terminal. Based on the capacitance of the capacitor C7, the soft start time is set.

  The stop unit 21 outputs a stop request signal under the control of the malfunction prevention unit 23 in a predetermined case, and stops the PFC control unit 13, the switch control unit 19, and the startup power supply unit 22.

  The activation power supply unit 22 is activated when the output voltage of the power factor correction circuit 4 received via the VDCIN terminal becomes equal to or higher than a predetermined value, and supplies the control power supply voltage Vcc to the DC-DC converter 5 from the Vcc terminal. .

  The malfunction prevention unit 23 controls the stop unit 21 when the control power supply voltage Vcc supplied from the startup power supply unit 22 is less than a predetermined value, and controls the power factor correction circuit 4 by the PFC control unit 13 and the switch control unit 19. The control of the DC-DC converter 5 and the supply of the control power supply voltage Vcc by the starting power supply unit 22 are stopped.

  The illumination power supply control circuit 10 having the above configuration is configured so that the high-side switch element Q2 and the low-side switch of the DC-DC converter 5 are supplied to the light emitting module 6 so as to supply a direct current corresponding to the dimming degree set by the dimmer 8. The element Q3 is turned on / off. The illumination power supply control circuit 10 monitors the current flowing through the light emitting element lines 6a and 6b and performs feedback control so that the current becomes a target current value corresponding to the dimming degree.

<Control of power factor improvement circuit 4 by power supply control circuit 10 for lighting>
Next, control of the power factor correction circuit 4 by the illumination power supply control circuit 10 will be described with reference to FIG. FIG. 2 shows a circuit diagram of the dimming degree signal input unit 11, the deep dimming signal output unit 12, and the PFC control unit 13 of the illumination power supply control circuit 10.

  As described above, the dimming signal input unit 11 inverts the PWM signal received from the DIM-IN terminal, adjusts the on-voltage, and outputs it. As shown in FIG. 2, the dimming signal input unit 11 includes, for example, a comparator CMP1, a switch element Q4, and resistors R8, R9, and R10.

  One input terminal (−) of the comparator CMP1 is connected to the DIM-IN terminal, and the other input terminal (+) is connected to the reference voltage V1. The output terminal of the comparator CMP1 is connected to the gate terminal of the switch element Q4. The switch Q4 is, for example, an NMOSFET having one end (drain) connected to one end of the resistor R8 and the other end (source) grounded. The other end of the resistor R8 is connected to the voltage Vref. The resistor R9 has one end connected to one end of the switch element Q4 and the other end grounded. The resistor R10 has one end connected to one end of the switch element Q4 and the other end connected to the output terminal of the dimming signal input unit 11.

  As shown in FIG. 1, the output terminal of the dimming signal input unit 11 is connected to a capacitor C6 via a DC-OUT terminal. As a result, the PWM signal output from the dimming degree signal input unit 11 is converted into a direct current. As a result, a DC voltage (a dimming voltage) corresponding to the dimming degree is supplied to the deep dimming signal output unit 12 and the dimming output unit 14. In the case of the configuration example shown in FIG. 2, this dimming voltage becomes lower as the dimming degree is set lower.

  The deep dimming signal output unit 12 outputs a deep dimming signal when the dimming voltage based on the dimming degree of the dimmer 8 is less than the dimming reference voltage. The dimming reference voltage is a voltage corresponding to the switching threshold. Hereinafter, the case where the deep dimming signal is output is also simply referred to as “deep dimming”.

  As shown in FIG. 2, the deep light control signal output unit 12 includes, for example, a comparator CMP2. One input terminal (+) of the comparator CMP2 is connected to the output terminal of the dimming signal input unit 11, and the other input terminal (−) is connected to the reference voltage V2. The reference voltage V2 is a dimming reference voltage as a switching threshold. The comparator CMP2 outputs an L level signal as a deep dimming signal when the voltage (dimming voltage) at the DC-OUT terminal is lower than the reference voltage V2.

  The PFC control unit 13 outputs a gate signal from a GD terminal connected to the gate terminal of the switch element Q1 of the power factor correction circuit 4, and controls the switch element Q1 to be in a conductive state or a cutoff state.

  As shown in FIG. 2, the PFC control unit 13 includes a timer unit 31, a gate signal output unit 32, a switch current determination unit 33, a zero cross detection unit 34, an overvoltage detection unit 35, and a signal gate unit 36. Have.

  The timer unit 31 is configured to output a first on-trigger signal every predetermined turn-on period while receiving the deep dimming signal from the deep dimming signal output unit 12. A detailed configuration example will be described later with reference to FIG.

  When the zero-cross detector 34 detects that the inductor current has become zero, it outputs a second on-trigger signal. As illustrated in FIG. 2, the zero-cross detection unit 34 includes, for example, a comparator CMP4 and a one-shot circuit 37. One input terminal (−) of the comparator CMP4 is connected to the ZCD terminal, and the other input terminal (+) is connected to the reference voltage V4. The ZCD terminal is a terminal for monitoring the current flowing through the inductor L1, and is connected to the monitoring winding L2 magnetically coupled to the inductor L1.

  The one-shot circuit 37 is connected to the output terminal of the comparator CMP4, and outputs a pulse signal having a predetermined width (for example, 100 nSec) when the comparator CMP4 outputs an H level signal.

  The signal gate unit 36 is configured to pass the second on-trigger signal when no deep dimming signal is received, and not to pass the second on-trigger signal when the deep dimming signal is received. Yes. As shown in FIG. 2, the signal gate unit 36 includes, for example, an AND gate AND1. One input terminal of the AND gate AND1 is connected to the output terminal of the zero cross detector 34, and the other input terminal is connected to the output terminal of the depth dimming signal output unit 12.

  The switch current determination unit 33 outputs a first off trigger signal when the voltage based on the current flowing through the switch element Q1 exceeds the turn-off threshold voltage. Here, the “voltage based on the current flowing through the switch element Q1” is a voltage that increases as the value of the current flowing through the switch element Q1 increases. In the configuration of FIG. 1, the switch element Q1 and the resistor R3 Is the voltage at the connection point. The turn-off threshold voltage is a voltage based on the product of the input rectified voltage monitored at the MULT terminal (output voltage of the rectifier circuit 3) and the DC voltage monitored at the VFB terminal (output voltage of the power factor correction circuit 4). .

  As shown in FIG. 2, the switch current determination unit 33 includes, for example, an error amplifier EA1, a multiplier (multiplier) 40, a comparator CMP5, and a NOT gate N1.

  The error amplifier EA1 has one input terminal (−) connected to the VFB terminal and the other input terminal (+) connected to the reference voltage V5. The VFB terminal is a terminal for monitoring the output voltage of the power factor correction circuit 4 and is connected to a connection point between the resistors R4 and R5 as shown in FIG.

  The multiplier 40 outputs a voltage (turn-off threshold voltage) obtained by multiplying the output voltage of the error amplifier EA1 by the voltage input to the MULT terminal. The MULT terminal is a terminal for monitoring the input rectified voltage output from the rectifier circuit 3, and is connected to the connection point of the resistor R1 and the resistor R2, as shown in FIG.

  In the comparator CMP5, one input terminal (−) is connected to the CS terminal, and the other input terminal (+) is connected to the output terminal of the multiplier 40. The CS terminal is a terminal for monitoring a current flowing through the switch element Q1, and is connected to a connection point between the switch element Q1 and the resistor R3 as shown in FIG. The comparator CMP5 outputs an L level signal when the voltage at the input terminal (−) is higher than the voltage at the input terminal (+).

  The NOT gate N1 is connected to the output terminal of the comparator CMP5 and inverts the signal level. When receiving the L level signal, the NOT gate N1 outputs an H level signal (first off trigger signal).

  The overvoltage detection unit 35 outputs a second off-trigger signal when the DC voltage output from the power factor correction circuit 4 exceeds a predetermined abnormality threshold voltage. Here, the abnormal threshold voltage is a voltage higher than the rated output voltage of the power factor correction circuit 4, and is set as a voltage of 110% to 120% of the rated output voltage, for example.

  As shown in FIG. 2, the overvoltage detection unit 35 includes, for example, a comparator CMP3. In the comparator CMP3, one input terminal (+) is connected to the VFB terminal, and the other input terminal (−) is connected to the reference voltage V3 corresponding to the abnormal threshold voltage. The comparator CMP3 outputs an H level signal (second off trigger signal) when the voltage at the input terminal (+) is higher than the voltage at the input terminal (−).

  When receiving the first on-trigger signal from the timer unit 31 or when receiving the second on-trigger signal from the signal gate unit 36, the gate signal output unit 32 outputs an on signal that makes the switch element Q1 conductive. To do. In this case, the gate signal output unit 32 continues to output the on signal until the first or second off trigger signal is received.

  On the other hand, when the gate signal output unit 32 receives the first off-trigger signal from the switch current determination unit 33 or receives the second off-trigger signal from the overvoltage detection unit 35, the gate signal output unit 32 puts the switch element Q1 in the cutoff state. Outputs an off signal. In this case, the gate signal output unit 32 continues to output the off signal until the first or second on trigger signal is received.

  At the time of deep light control, the signal gate unit 36 does not pass the output of the zero cross detection unit 34, so that the detection of the zero cross of the inductor current is not notified to the gate signal output unit 32. Therefore, at the time of deep light control, the gate signal output unit 32 outputs an ON signal using only the first ON trigger signal output from the timer unit 31 every turn-on cycle as a trigger. Thereby, at the time of deep light control, the illumination power supply control circuit 10 performs switching control with a fixed turn-on cycle.

  As shown in FIG. 2, the gate signal output unit 32 includes, for example, an SR type flip-flop 38 having set input terminals S1, S2 and reset input terminals R1, R2. When the H level signal is input to the set input terminal S1 or S2, the SR flip-flop 38 holds the output of the H level signal from the output terminal Q, and the H level signal is input to the reset input terminal R1 or R2. Then, the output of the L level signal from the output terminal Q is held.

  The gate signal output unit 32 further includes a gate driver 39 that adjusts the level of the voltage of the H level signal output from the SR flip-flop 38 to a voltage suitable for the switch element Q1 and outputs the voltage to the GD terminal. Good.

  Next, the detailed configuration of the timer unit 31 will be described with reference to FIG. As shown in FIG. 3, the timer unit 31 includes a constant current source I1, a comparator CMP6, a current supply switch element Q5, a capacitor C9, and a discharge switch element Q6.

  The comparator CMP6 includes a first input terminal (+), a second input terminal (−) connected to a predetermined reference voltage V6, and the voltage at the first input terminal is higher than the voltage at the second input terminal. And an output terminal for outputting a first on-trigger signal. The output terminal of the comparator CMP6 is connected to the set input terminal S1 of the SR flip-flop 38.

  One end of the current supply switch element Q5 is connected to the output terminal of the constant current source I1, the other end is connected to the first input terminal (+) of the comparator CMP6, and the gate terminal is the depth dimming signal output unit 12. Is connected to the output terminal. The current supply switch element Q5 is, for example, a PMOSFET. When the gate terminal receives the deep dimming signal (L level signal), the current supply switch element Q5 becomes conductive.

  One end of the capacitor C9 is connected to the other end (drain) of the current supply switch element Q5, and the other end is grounded.

  One end of the discharging switch element Q6 is connected to one end of the capacitor C9, the other end is grounded, and the gate terminal is connected to the output terminal Q of the SR flip-flop 38. The discharging switch element Q6 is, for example, an NMOSFET. When the gate signal output unit 32 outputs an ON signal (that is, when the SR flip-flop 38 outputs an H level signal), the discharging switch element Q6 becomes conductive.

  The timer unit 31 configured as described above operates as follows. When the deep dimming signal output unit 12 outputs the deep dimming signal, the switch element Q5 becomes conductive, and electric charges start to be accumulated in the capacitor C9. As charge is accumulated in the capacitor C9, the voltage at the input terminal (+) of the comparator CMP6 increases. When the voltage at the input terminal (+) exceeds the reference voltage V6, the comparator CMP6 outputs an H level signal (first on trigger signal).

  When the first on-trigger signal is received, the SR flip-flop 38 outputs an H level signal (on signal) from the output terminal Q. As a result, the discharging switch element Q6 becomes conductive, and the capacitor C9 is discharged. After that, when the current flowing through the switch element Q1 reaches the turn-off threshold voltage and the SR flip-flop 38 outputs an L level signal, the discharge switch element Q6 is cut off, and the constant current source I1 charges the capacitor C9 again. As a result, the voltage at the input terminal (+) of the comparator CMP6 rises. When the voltage at the input terminal (+) exceeds the reference voltage V6, the comparator CMP6 outputs an H level signal (first on trigger signal).

  By repeating the above operation, the timer unit 31 outputs the first on-trigger signal every predetermined turn-on period Ton while receiving the deep dimming signal from the deep dimming signal output unit 12. Note that the timer unit 31 does not count time because the discharge switch element Q6 is also in a conductive state while the switch element Q1 is in a conductive state. However, since the ON width of the switch element Q1 is the minimum ON width (constant value) at the time of deep dimming, the first ON trigger signal is a constant time interval Ton (the sum of the charging time of the capacitor C9 and the minimum ON width). ) Will be output.

  The length of the turn-on cycle Ton can be adjusted to a desired length by appropriately selecting the output current of the constant current source I1 of the timer unit 31, the capacitance of the capacitor C9, and the value of the reference voltage V6. .

  Further, the turn-on cycle Ton is preferably set so that the switching frequency of the switching element Q1 in the fixed frequency control is higher than the upper limit frequency of the audible region, and is preferably 50 μSec or less (20 kHz or more), for example.

  Further, as shown in FIG. 3, a constant current source I <b> 2 may be provided in the timer unit 31 in order to provide the timer unit 31 with a restart timer function. The output terminal of the constant current source I2 is connected to one end of the capacitor C9. As a result, even when the zero crossing of the inductor current is not normally detected due to disconnection or sudden change in input, the output of the power factor correction circuit 4 is controlled by controlling the switch element Q1 to be conductive at a predetermined restart period (for example, 100 μSec). Can be prevented from becoming zero.

  Next, a PFC control unit 13A having a timer unit 31A having a configuration different from that of the timer unit 31 will be described with reference to FIG. The timer unit 31A of the PFC control unit 13A outputs a first on-trigger signal for each turn-on period during deep dimming.

  As shown in FIG. 4, the timer unit 31A includes a constant current source I1, a comparator CMP6, a capacitor C9, and a discharging switch element Q6.

  The comparator CMP6 includes a first input terminal (+), a second input terminal (−) connected to a predetermined reference voltage V6, and the voltage at the first input terminal is higher than the voltage at the second input terminal. And an output terminal for outputting a first on-trigger signal.

  One end of the capacitor C9 is connected to the output terminal of the constant current source I1 and the first input terminal of the comparator CMP6, and the other end is grounded.

  One end of the discharging switch element Q6 is connected to one end of the capacitor C9, the other end is grounded, and the gate terminal is connected to the output terminal Q of the SR flip-flop 38. When the gate signal output unit 32 outputs an ON signal (that is, when the SR flip-flop 38 outputs an H level signal), the discharging switch element Q6 becomes conductive.

  In the PFC control unit 13A having the timer unit 31A, when the deep dimming signal is not received from the deep dimming signal output unit 12, the signal gate unit 36 passes the second on-trigger signal. Each time it becomes zero, the discharging switch element Q6 becomes conductive, and the capacitor C9 is discharged. Since the capacitor C9 is discharged before the voltage at one end of the capacitor C9 becomes higher than the reference voltage V6, the timer unit 31A does not output the first on-trigger signal.

  On the other hand, when the deep dimming signal is received from the deep dimming signal output unit 12, that is, during the deep dimming, the signal gate unit 36 does not pass the second on-trigger signal, so that the capacitor C9 has a zero crossing of the inductor current. It is not discharged at the timing. Therefore, the timer unit 31A outputs the first on trigger signal for each turn-on period.

  The illumination power supply control circuit 10 includes the PFC control unit 13 including the zero-cross detection unit 34, the switch current determination unit 33, and the gate signal output unit 32, so that the dimming degree is equal to or higher than a predetermined switching threshold. And current criticality control. In the current critical control, when the inductor current decreases to zero, the PFC control unit 13 controls the switch element Q1 to be in a conductive state to increase the inductor current, and when the voltage based on the current flowing through the switch element Q1 reaches the turn-off threshold voltage. The inductor element is decreased by controlling the switch element Q1 to the cut-off state.

  The illumination power supply control circuit 10 includes PFC control units 13 and 13A having timer units 31 and 31A, a switch current determination unit 33, a signal gate unit 36, and a gate signal output unit 32. When the dimming degree is less than a predetermined switching threshold (deep dimming), fixed frequency control is performed. In this fixed frequency control, the PFC control unit 13 controls the switch element Q1 to be in a conductive state forcibly every predetermined turn-on cycle Ton.

  The turn-on cycle Ton is set so that the number of turn-on times of the switch element Q1 per cycle of the input AC voltage is smaller than the number of turn-on times in the current critical mode. In other words, the turn-on cycle Ton is set such that an off period in which the inductor current is zero occurs.

  Further, the illumination power supply control circuit 10 includes an overvoltage detection unit 35 so that an overvoltage protection function is implemented. That is, when the output voltage of the power factor correction circuit 4 exceeds the abnormal threshold voltage, the illumination power supply control circuit 10 forcibly controls the switch element Q1 to be in a cut-off state, thereby outputting the output of the power factor improvement circuit 4 Reduce voltage.

  Next, with reference to FIG. 5, the PFC operation | movement waveform of the lighting fixture 1 provided with the power supply control circuit 10 for illumination which has the said structure is demonstrated.

  The upper part of FIG. 5 shows a waveform (one period) of the input AC voltage of the AC power supply 2. The middle stage of FIG. 5 shows the PFC operation waveforms (the waveforms of the inductor current IL and the input current Iin) when the power factor correction circuit 4 outputs the rated voltage, that is, not during the dimming. . The inductor current IL has a waveform subjected to current critical control. The input current Iin has a waveform substantially similar to the input AC voltage by the power factor correction circuit 4.

  The lower part of FIG. 5 shows PFC operation waveforms (waveforms of inductor current IL and input current Iin) during deep dimming.

  As shown in the lower part of FIG. 5, the inductor current IL starts to rise every turn-on period Ton. Also, the inductor current IL does not rise immediately like current critical control after dropping to zero, but remains zero until the turn-on cycle elapses. That is, an off period in which the inductor current is zero occurs in the waveform of the inductor current IL. In addition, when the off period occurs, the input current Iin becomes a lower value than the rated time as shown in the lower part of FIG.

  As described above, the illumination power supply control circuit 10 according to the present embodiment controls the switch element Q1 to be in a conductive state after a predetermined turn-on cycle Ton has passed during deep dimming, and the inductor current IL is zero. An off period occurs. Thereby, an increase in the output voltage of the power factor correction circuit 4 can be suppressed. As a result, it is possible to prevent the overvoltage protection function from being activated and to prevent the power factor from being lowered.

  In the above description, the turn-on cycle is fixed, but may be changed according to the dimming degree. More specifically, the turn-on cycle Ton may be continuously increased as the dimming degree is lowered. For example, the depth dimming signal output unit 12 is configured by an error amplifier instead of the comparator CMP2, and the depth dimming signal output unit 12 is configured to output a voltage corresponding to the difference between the dimming voltage and the reference voltage V2. To do. As a result, the current flowing through the switching element Q5 of the timer unit 31 changes according to the dimming voltage, and the charge accumulation speed in the capacitor C9 changes. In addition, the turn-on period Ton may be increased stepwise as the dimming level decreases.

  As described above, in the first embodiment, when the dimming degree is less than the switching threshold (deep dimming), the number of turn-ons of the switch element Q1 per cycle of the input AC voltage is the turn-on in the current critical mode. Fixed frequency control is performed in which the switch element Q1 is forcibly controlled to be in a conductive state at a predetermined turn-on cycle Ton so as to be less than the number of times.

  As a result, an off period is generated in the inductor current IL, an increase in the output voltage of the power factor correction circuit 4 is suppressed, and the switch element Q1 can be prevented from being forcibly controlled to be cut off by the overvoltage protection function. .

  Therefore, according to the present embodiment, it is possible to prevent the switching operation of the switch element Q1 from being stopped / restarted during the deep dimming, and to prevent the harmonic component of the input current Iin from being generated or increased. . Therefore, according to the first embodiment, it is possible to prevent the power factor from being lowered during the deep light control.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. One of the differences between the second embodiment and the first embodiment is that an output voltage monitoring unit that monitors the output voltage of the power factor correction circuit 4 is provided in the PFC control unit of the illumination power supply control circuit 10. It is provided.

  As shown in FIG. 6, the PFC control unit 13B according to the second embodiment includes a timer unit 31B, a gate signal output unit 32, a switch current determination unit 33, a zero cross detection unit 34, and an overvoltage detection unit 35. , A signal gate unit 36, an output voltage monitoring unit 41, and a signal gate unit 42.

  Note that the switch current determination unit 33, the zero-cross detection unit 34, and the overvoltage detection unit 35 are the same as those in the first embodiment, and thus detailed description thereof is omitted.

  The timer unit 31B of the PFC control unit 13B outputs the first on-trigger signal for each turn-on period while receiving the deep dimming signal from the signal gate unit 42. The specific configuration of the timer unit 31B is the same as that of the timer unit 31 described with reference to FIG.

  The output voltage monitoring unit 41 is configured to output an output voltage increase signal when the DC voltage output from the power factor correction circuit 4 is higher than a predetermined warning threshold voltage.

  Here, the warning threshold voltage is a voltage between the rated output voltage of the power factor correction circuit 4 and the output voltage (abnormal threshold voltage) at which the overvoltage protection function operates. That is, the warning threshold voltage is higher than the rated output voltage of the power factor correction circuit 4 and lower than the abnormal threshold voltage. For example, the warning threshold voltage is set to a voltage of 105% to 110% of the rated output voltage.

  As illustrated in FIG. 6, the output voltage monitoring unit 41 includes, for example, a comparator CMP7. In the comparator CMP7, one input terminal (−) is connected to the VFB terminal, and the other input terminal (+) is connected to the reference voltage V7 corresponding to the warning threshold voltage. The comparator CMP7 outputs an L level signal as an output voltage increase signal when the voltage at the input terminal (−) is higher than the voltage at the input terminal (+).

  The signal gate unit 42 passes the deep dimming signal when the output voltage increase signal is received, and does not pass the deep dimming signal when the output voltage increase signal is not received. As illustrated in FIG. 6, the signal gate unit 42 includes, for example, an OR gate OR1. One input terminal of the OR gate OR1 is connected to the output terminal of the deep light control signal output unit 12, and the other input terminal is connected to the output terminal of the comparator CMP7. The output terminal of the OR gate OR1 is connected to the gate terminal of the switch element Q5 of the timer unit 31B and the input terminal of the AND gate AND1 of the signal gate unit 36.

  The signal gate unit 36 allows the second on-trigger signal to pass when no deep dimming signal is received from the signal gate unit 42, and the second gate signal when the deep dimming signal is received from the signal gate unit 42. Do not allow the on-trigger signal to pass. The signal gate unit 36 is composed of, for example, an AND gate AND1. As shown in FIG. 6, one input terminal of the AND gate AND <b> 1 is connected to the output terminal of the zero cross detection unit 34, and the other input terminal is connected to the output terminal of the signal gate unit 42.

  When receiving the first on-trigger signal from the timer unit 31B or receiving the second on-trigger signal from the signal gate unit 36, the gate signal output unit 32 outputs an on signal that makes the switch element Q1 conductive. To do. Further, when the gate signal output unit 32 receives the first off-trigger signal from the switch current determination unit 33 or receives the second off-trigger signal from the overvoltage detection unit 35, the gate signal output unit 32 puts the switch element Q1 into the cutoff state. Outputs an off signal.

  In the PFC control unit 13B having the above configuration, even when the deep dimming signal is received, if the DC voltage output from the power factor correction circuit 4 is less than the warning threshold voltage, the comparator CMP7 outputs the H level signal. Therefore, the signal gate unit 42 blocks the deep dimming signal. For this reason, the switching element Q5 of the timer unit 31B does not become conductive, and the signal gate unit 36 allows the second on-trigger signal to pass. Therefore, the PFC control unit 13B performs current critical control similarly to the case where the dimming degree is equal to or higher than the switching threshold.

  On the other hand, when the deep dimming signal is received and the DC voltage output from the power factor correction circuit 4 is equal to or higher than a predetermined warning threshold voltage, the comparator CMP7 outputs an L level signal, so the signal gate unit 42 Passes the dimming signal. For this reason, the switch element Q5 of the timer unit 31B enters a conductive state and starts a timer operation. The signal gate unit 36 blocks the second on trigger signal. Therefore, the PFC control unit 13B performs the above-described fixed frequency control.

  As described above, when the PFC control unit 13B according to the second embodiment receives the deep dimming signal and the DC voltage output from the power factor correction circuit 4 is equal to or higher than the predetermined warning threshold voltage. The fixed frequency control is performed, and the current critical control is performed in other cases.

  According to the second embodiment, similarly to the first embodiment, it is possible to prevent the power factor from being lowered due to the stop / restart of the switching operation of the switch element Q1 during deep dimming.

  Further, in the second embodiment, even when the dimming degree is lowered and the output voltage of the power factor correction circuit 4 is increased, if the output increase is such that the overvoltage protection function is not activated, the current critical control is performed as it is. I do. When the output voltage further rises and reaches the warning threshold voltage, the process shifts to fixed frequency control.

  Thus, according to the second embodiment, the transition from the current critical control to the fixed frequency control can be accurately performed, and a high power factor by the current critical control can be maintained in a wider dimming range.

  Next, a modification of the second embodiment will be described with reference to FIG. In the PFC control unit 13C according to this modification, the configuration of the timer unit 31C is different. As shown in FIG. 7, the timer unit 31C of the PFC control unit 13C has the same configuration as the timer unit 31A described in FIG. In the case of this modification, the output terminal of the signal gate unit 42 is connected only to the input terminal of the AND gate AND1 of the signal gate unit 36 and is not connected to the timer unit 31C. The timer unit 31C outputs a first on-trigger signal for each turn-on period regardless of whether or not a deep dimming signal is received.

  In the PFC control unit 13C according to the present modified example, when the deep dimming signal is not received from the deep dimming signal output unit 12, or the deep dimming signal is received, the output voltage increase signal is received. If not, the signal gate unit 36 passes the second on-trigger signal. For this reason, every time the inductor current becomes zero, the discharging switch element Q6 becomes conductive and the capacitor C9 is discharged. Since the charging time of the capacitor C9 is set to be longer than the zero-crossing interval of the inductor current, the timer unit 31C does not output the first on trigger signal.

  On the other hand, when the deep dimming signal is received from the deep dimming signal output unit 12 and the output voltage increase signal is received from the output voltage monitoring unit 41, the signal gate unit 36 receives the second on-trigger signal. Do not pass. Therefore, the timer unit 31C outputs the first on trigger signal for each turn-on period. Also according to this modification, it is possible to obtain an effect that the transition from the current critical control to the fixed frequency control can be performed with high accuracy and a high power factor by the current critical control can be maintained in a wider dimming range.

  Based on the above description, those skilled in the art may be able to conceive additional effects and various modifications of the present invention, but the aspects of the present invention are not limited to the individual embodiments described above. . You may combine suitably the component covering different embodiment. Various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the present invention derived from the contents defined in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Lighting fixture 2 AC power supply 3 Rectifier circuit 4 Power factor improvement circuit 5 DC-DC converter 6 Light emitting module 6a, 6b Light emitting element line 7 Light emitting element 8 Dimmer 9 Light control signal receiver 10 Lighting power supply control circuit 11 Light control Signal input unit 12 Depth dimming signal output unit 13, 13A, 13B, 13C PFC control unit 14 Dimming output unit 15 Oscillator 16 Operational amplifier 17 Comparator 18 Control unit 19 Switch control unit 20 Soft start unit 21 Stop unit 22 Start power supply unit 23 Malfunction prevention unit 31, 31A, 31B, 31C Timer unit 32 Gate signal output unit 33 Switch current determination unit 34 Zero cross detection unit 35 Overvoltage detection unit 36 Signal gate unit 37 One-shot circuit 38 SR flip-flop 39 Gate driver 40 Multiplier (Multiplier)
41 output voltage monitoring unit 42 signal gate unit AND1 AND gates C1, C2, C3, C4, C5, C6, C7, C8, C9 capacitors CMP1, CMP2, CMP3, CMP4, CMP5, CMP6, CMP7 comparators D1, D2, D3, D4, D5, D6, D7, D8 Diode EA1 Error amplifier I1, I2 Current source L1 Inductor L2 Monitor winding L3 Primary winding L4 Secondary winding N1 NOT gate OR1 OR gate PC1 Photocoupler P1 Light emitting diode P2 Phototransistors Q1, Q2, Q3, Q4, Q5, Q6 Switch elements R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11 Resistors Ra, Rb, Rc, Rd, Re, Rf Resistor T Transformer V1, V2, V3, V4, V5, V6, V7 Reference voltage

Claims (15)

A rectifier circuit that rectifies and smoothes an input AC voltage output from an AC power supply and outputs an input rectified voltage; an inductor; and a switch element that controls an inductor current flowing through the inductor; and the input rectification by a switching operation of the switch element. A power factor improvement circuit that converts a voltage into a DC voltage, and a DC-DC converter that outputs a DC current based on the DC voltage to a light emitting module having a current injection type light emitting element. Power supply control circuit,
When the dimming degree of the light emitting module set by the dimmer is equal to or higher than a predetermined switching threshold value, current critical control is performed to control the switch element to a conductive state when the inductor current becomes zero,
When the dimming degree is less than the switching threshold, the switch element is turned on at a predetermined turn-on cycle so that the number of turn-on times of the switch element per cycle of the input AC voltage is less than the number of turn-on times in the current critical mode. To perform fixed frequency control to control the conduction state with
An illumination power supply control circuit.   The current critical control is performed instead of the fixed frequency control when the dimming degree is less than the switching threshold value and the DC voltage is less than a voltage at which an overvoltage protection function operates. The illumination power supply control circuit according to 1.   3. The illumination power supply control circuit according to claim 1, wherein the turn-on period is set such that a switching frequency of the switch element in the fixed frequency control is higher than an upper limit frequency of an audible region. .   The illumination power supply control circuit according to claim 1, wherein the turn-on period continuously increases as the dimming degree decreases.   The said DC-DC converter controls the said DC-DC converter so that the direct current according to the light control degree of the said light emitting module may be output to the said light emitting module. Power control circuit for lighting.   6. The illumination power supply control circuit according to claim 1, wherein the light emitting element is a light emitting diode, a laser diode, an organic EL element, or another semiconductor light emitting element. A dimming signal output unit for outputting a dimming signal when the dimming voltage based on the dimming degree of the dimmer is less than a dimming reference voltage corresponding to the switching threshold;
A PFC control unit that performs the fixed frequency control when the depth dimming signal is received, and performs the current critical control when the depth dimming signal is not received;
The illumination power supply control circuit according to claim 1, further comprising: The PFC control unit
A timer unit that outputs a first on-trigger signal every turn-on period while receiving the deep dimming signal;
A zero-cross detector that outputs a second on-trigger signal when detecting that the inductor current has become zero;
A signal gate section that passes the second on-trigger signal when not receiving the deep dimming signal, and that does not pass the second on-trigger signal when receiving the deep dimming signal;
A switch current determination unit that outputs a first off-trigger signal when a voltage based on a current flowing through the switch element exceeds a turn-off threshold voltage based on a product of the input rectified voltage and the DC voltage;
An overvoltage detector that outputs a second off-trigger signal when the DC voltage exceeds an abnormal threshold voltage that is higher than the rated output voltage of the power factor correction circuit;
When the first on-trigger signal is received from the timer unit or when the second on-trigger signal is received from the signal gate unit, an on signal for turning on the switch element is output, and the switch current A gate signal output unit that outputs an off signal that turns off the switch element when the first off trigger signal is received from the determination unit or the second off trigger signal is received from the overvoltage detection unit; ,
The illumination power supply control circuit according to claim 7, further comprising: The timer unit is
A constant current source;
The first on-trigger signal when the voltage of the first input terminal, the second input terminal connected to a predetermined reference voltage, and the voltage of the first input terminal are larger than the voltage of the second input terminal A comparator having an output terminal for outputting
One end is connected to the output terminal of the constant current source, the other end is connected to the first input terminal of the comparator, a gate terminal is connected to the output terminal of the depth dimming signal output unit, and the gate terminal A switch element for supplying current that becomes conductive when receiving the deep dimming signal;
A capacitor having one end connected to the other end of the current supply switch element and the other end grounded;
One end is connected to one end of the capacitor, the other end is grounded, and the discharging switch element that becomes conductive when the gate signal output unit outputs the ON signal;
The illumination power supply control circuit according to claim 8, comprising: The timer unit is
A constant current source;
The first on-trigger signal when the voltage of the first input terminal, the second input terminal connected to a predetermined reference voltage, and the voltage of the first input terminal are larger than the voltage of the second input terminal A comparator having an output terminal for outputting
A capacitor having one end connected to the output terminal of the constant current source and the first input terminal of the comparator, and the other end grounded;
One end is connected to one end of the capacitor, the other end is grounded, and the discharging switch element that becomes conductive when the gate signal output unit outputs the ON signal;
The illumination power supply control circuit according to claim 8, comprising: A dimming signal output unit for outputting a dimming signal when the dimming voltage based on the dimming degree of the dimmer is less than a dimming reference voltage corresponding to the switching threshold;
When the depth dimming signal is received and the DC voltage is higher than a warning threshold voltage between a rated output voltage of the power factor correction circuit and an abnormal threshold voltage at which an overvoltage protection function operates, the fixed frequency A PFC control unit that performs control, and otherwise performs the current critical control;
The illumination power supply control circuit according to claim 1, further comprising: The PFC control unit
When the DC voltage is higher than the warning threshold voltage, an output voltage monitoring unit that outputs an output voltage increase signal;
A first signal gate that passes the depth dimming signal when receiving the output voltage rise signal, and does not pass the depth dimming signal when the output voltage rise signal is not received;
A timer unit that outputs a first on-trigger signal for each turn-on period while receiving the deep dimming signal from the first signal gate unit;
A zero-cross detector that outputs a second on-trigger signal when detecting that the inductor current has become zero;
When the depth dimming signal is not received from the first signal gate unit, the second on-trigger signal is passed, and when the depth dimming signal is received from the first signal gate unit. A second signal gate portion that does not pass the second on-trigger signal;
A switch current determination unit that outputs a first off-trigger signal when a voltage based on a current flowing through the switch element exceeds a turn-off threshold voltage based on a product of the input rectified voltage and the DC voltage;
An overvoltage detector that outputs a second off-trigger signal when the DC voltage exceeds the abnormal threshold voltage;
When the first on-trigger signal is received from the timer unit or when the second on-trigger signal is received from the second signal gate unit, an on signal for turning on the switch element is output, When receiving the first off-trigger signal from the switch current determination unit or when receiving the second off-trigger signal from the overvoltage detection unit, a gate signal that outputs an off signal that turns off the switch element An output section;
The illumination power supply control circuit according to claim 11, comprising:   13. A semiconductor integrated circuit, wherein the illumination power supply control circuit according to claim 1 is formed on a predetermined semiconductor substrate. A rectifying circuit that rectifies and smoothes the input AC voltage output from the AC power supply and outputs the input rectified voltage;
A power factor improving circuit that includes an inductor and a switching element that controls an inductor current flowing through the inductor, and converts the input rectified voltage into a DC voltage by a switching operation of the switching element;
A DC-DC converter that outputs a direct current based on the direct current voltage to a light emitting module having a current injection type light emitting element;
When the dimming degree of the light emitting module set by the dimmer is equal to or greater than a predetermined switching threshold, current critical control is performed to control the switch element to a conductive state when the inductor current becomes zero, When the dimming degree is less than the switching threshold, the switch element is turned on at a predetermined turn-on period so that the turn-on number of the switch element per period of the input AC voltage is less than the turn-on number in the current critical mode. A power supply control circuit for lighting that performs fixed frequency control for forcibly controlling to a conductive state;
An illumination power source comprising: A light emitting module having a current injection type light emitting element;
A rectifying circuit that rectifies and smoothes the input AC voltage output from the AC power supply and outputs the input rectified voltage;
A power factor improving circuit that includes an inductor and a switching element that controls an inductor current flowing through the inductor, and converts the input rectified voltage into a DC voltage by a switching operation of the switching element;
A DC-DC converter that outputs a direct current based on the direct current voltage to the light emitting module;
When the dimming degree of the light emitting module set by the dimmer is equal to or greater than a predetermined switching threshold, current critical control is performed to control the switch element to a conductive state when the inductor current becomes zero, When the dimming degree is less than the switching threshold, the switch element is turned on at a predetermined turn-on period so that the turn-on number of the switch element per period of the input AC voltage is less than the turn-on number in the current critical mode. A power supply control circuit for lighting that performs fixed frequency control for forcibly controlling to a conductive state;
A lighting apparatus comprising:

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