CN222030101U - Code-pulling current-regulating LED circuit - Google Patents

Abstract

The utility model discloses a code pulling and current regulating LED circuit, which comprises a live wire input end L, a zero line input end N, a safety circuit F1, a lightning protection surge circuit, a rectifying circuit, a filtering circuit, a constant current IC control circuit, an output no-load control circuit, a code pulling switch current regulating circuit, a high-frequency oscillation output circuit, an LED working filtering circuit and an LED working circuit, wherein the lightning protection surge circuit comprises a piezoresistor RV1, the rectifying circuit comprises a rectifier bridge DB1, the piezoresistor RV1 is connected between the live wire input end L and the zero line input end N, the cost is low, a single chip integrated current regulating function is realized, the code pulling switch current regulating circuit does not influence OVP voltage, a circuit structure is optimized, the code pulling current regulating range reaches 40% -100%, peripheral auxiliary components of the IC are reduced, the design is simpler and more convenient, the cost is lower, and the performance is more stable. The operation is simple, and the production efficiency is improved.

Description

Code-pulling current-regulating LED circuit

Technical Field

The utility model relates to the technical field of lighting equipment, in particular to a code-pulling current-regulating LED circuit.

Background

LED (light emitting diode) lighting has been popular and has contributed to the great energy saving of society. The LED circuits currently used in the market are all constant current circuits, i.e. the current supplied to the operation of the LED is constant.

LED lighting devices widely used in the market at present generally employ a constant current driving circuit. Constant current drive can ensure that the LED lamp beads keep stable brightness within a certain range, and meanwhile, the service life of the LED lamp beads is prolonged. However, constant current driving also has some inconveniences:

The cost is higher: the constant current driving circuit requires additional components such as inductance, capacitance, etc., which increases the overall cost.

Compatibility problem: different LED lamp beads may have different voltage and current requirements, and the constant current driving circuit may not fully utilize the luminous efficiency of the LED lamp beads, thereby affecting the overall lighting effect.

And (3) installation and maintenance: the constant current drive circuit requires specialized installation and debugging, and once a failure occurs, specialized maintenance is required.

The adaptability is limited: constant current drive circuits are typically optimized for only a specific operating current, and their suitability may be limited for different operating conditions and environmental factors.

A circuit for pulling out the code and adjusting the current is developed at present, different output currents can be selected by the circuit, the brightness of the lamplight can be better adjusted, and the circuit has market competitiveness.

Disclosure of utility model

The utility model aims to provide a code-pulling current-regulating LED circuit which can select different output currents and better regulate the brightness of lamplight. And has market competitiveness to solve the problems in the prior art.

In order to achieve the above purpose, the present utility model provides the following technical solutions: the code pulling and current regulating LED circuit comprises a live wire input end L, a zero line input end N, a safety circuit F1, a lightning protection surge circuit, a rectifying circuit, a filtering circuit, a constant current IC control circuit, an output no-load control circuit, a code pulling switch current regulating circuit, a high-frequency oscillation output circuit, an LED working filtering circuit and an LED working circuit, wherein the lightning protection surge circuit comprises a piezoresistor RV1, the rectifying circuit comprises a rectifying bridge DB1, the piezoresistor RV1 is connected between the live wire input end L and the zero line input end N, one end of the safety circuit F1 is electrically connected with the live wire input end L, the other end of the safety circuit F1 is respectively connected with one end of the piezoresistor RV1 and the 4 pins of the rectifying bridge DB1, the 1 pin of the rectifying bridge DB1 is electrically connected with the zero line input end N, the filtering circuit comprises a capacitor C1, 3 pins of a rectifier bridge DB1 of the rectifying circuit are connected with the positive electrode of the capacitor C1, the filtering circuit is respectively connected with a constant-current IC control circuit, an output no-load control circuit, a code pulling switch current adjusting circuit, an LED working filtering circuit and an LED working circuit, the constant-current IC control circuit is respectively connected with the output no-load control circuit, the code pulling switch current adjusting circuit and a high-frequency oscillation output circuit, the LED working filtering circuit is respectively connected with the LED working circuit and the high-frequency oscillation output circuit, the constant-current IC control circuit comprises an LED constant-current driving chip IC, the LED constant-current driving chip comprises an LED+ -LED-lamp bead string, and the LED working filtering circuit comprises a load resistor R3 and a capacitor C2 connected with two ends of the load resistor R3 in parallel.

Preferably: the LED constant current driving chip IC comprises a GND pin, an NC pin, a ROVP pin, a DIM pin, an HV pin, a DRAIN pin, a SOURCE pin and a CS pin, the output no-load control circuit comprises a resistor R2, the code pulling switch current adjusting circuit comprises a code pulling switch DIP, the constant current IC control circuit further comprises a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a capacitor C3, the high-frequency oscillation output circuit comprises a diode D1 and a transformer T1, and the resistor R1 is an internal MOS current sampling resistor.

Preferably: the 2 feet of the rectifier bridge DB1 are simultaneously connected with one end of a resistor R1, a capacitor C1, a GND pin of an LED constant current driving chip IC, a resistor R2, a resistor R5, a resistor R6, a resistor R7 and a capacitor C3 respectively, the 3 feet of the rectifier bridge DB1 are also connected with one ends of a diode D1, an LED+ -LED-lamp bead string, a load resistor R3, a capacitor C2 and a resistor R4, the other ends of the LED+ -LED-lamp bead string, the load resistor R3 and the capacitor C2 are connected with one end of a transformer T1, and the other end of the diode D1 is connected with the DRAIN pin of the LED constant current driving chip IC and the other end of the transformer T1 respectively.

Preferably: the other end of the resistor R1 is connected with the SOURCE pin and the CS pin of the LED constant current driving chip IC, the other end of the resistor R4 is connected with the HV pin of the LED constant current driving chip IC, the other end of the resistor R2 is connected with the ROVP pin of the LED constant current driving chip IC, the other ends of the resistor R6 and the resistor R7 are connected with one end of the DIP switch, and the other ends of the capacitor C1, the DIP switch DIP and the resistor R5 are connected with the DIM pin of the LED constant current driving chip IC.

Preferably: the fuse wire F1 is a fuse/PTC thermistor.

Preferably: the model of the LED constant current driving chip IC is IC2872TS.

Compared with the prior art, the utility model has the beneficial effects that:

1. The utility model has low cost, and the single chip integrates the current regulating function.

2. The dialing switch regulates current without affecting the OVP voltage.

3. The circuit does not need too many peripheral auxiliary devices, and the circuit structure is optimized.

4. The current range of dialing code is 40% -100%

5. The IC peripheral auxiliary components are reduced, so that the design is simpler and more convenient, the cost is lower, and the performance is more stable. The operation is simple, and the production efficiency is improved.

Drawings

FIG. 1 is a schematic circuit diagram of the present utility model;

FIG. 2 is a diagram showing the IC pin distribution of the LED constant current driving chip;

FIG. 3 is an internal block diagram of an LED constant current driving chip IC of the present utility model;

FIG. 4 is a schematic electrical schematic diagram of the present utility model;

FIG. 5 is a graph showing the relationship between the DIM voltage and the reference voltage of the CS comparator according to the present utility model;

fig. 6 is a schematic diagram of a PCB board according to the present utility model.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Examples

Referring to fig. 1-6, the present utility model provides a technical solution: the code pulling and current regulating LED circuit comprises a live wire input end L, a zero line input end N, a safety circuit F1, a lightning protection surge circuit, a rectifying circuit, a filtering circuit, a constant current IC control circuit, an output no-load control circuit, a code pulling switch current regulating circuit, a high-frequency oscillation output circuit, an LED working filtering circuit and an LED working circuit, wherein the lightning protection surge circuit comprises a piezoresistor RV1, the rectifying circuit comprises a rectifying bridge DB1, the piezoresistor RV1 is connected between the live wire input end L and the zero line input end N, one end of the safety circuit F1 is electrically connected with the live wire input end L, the other end of the safety circuit F1 is respectively connected with one end of the piezoresistor RV1 and the 4 pins of the rectifying bridge DB1, the 1 pin of the rectifying bridge DB1 is electrically connected with the zero line input end N, the filtering circuit comprises a capacitor C1, 3 pins of a rectifier bridge DB1 of the rectifying circuit are connected with the positive electrode of the capacitor C1, the filtering circuit is respectively connected with a constant-current IC control circuit, an output no-load control circuit, a code pulling switch current adjusting circuit, an LED working filtering circuit and an LED working circuit, the constant-current IC control circuit is respectively connected with the output no-load control circuit, the code pulling switch current adjusting circuit and a high-frequency oscillation output circuit, the LED working filtering circuit is respectively connected with the LED working circuit and the high-frequency oscillation output circuit, the constant-current IC control circuit comprises an LED constant-current driving chip IC, the LED constant-current driving chip comprises an LED+ -LED-lamp bead string, and the LED working filtering circuit comprises a load resistor R3 and a capacitor C2 connected with two ends of the load resistor R3 in parallel.

Product characteristics

(1) Integrating a high-voltage JFET, and integrating a high-voltage 500V power MOS tube without a VCC capacitor and a starting resistor;

(2) The current regulation of the dial switch does not influence the OVP voltage;

(3) A built-in 500V power switch;

(4) Output current accuracy of + -5% LEDs;

(5) LED short-circuit protection and LED open-circuit protection;

(6) A superheat regulating function;

(7) Chip power supply under-voltage protection;

(8) The four-gear OVP voltage is 135V, 225V, 320V without limitation;

(9) The current range of dialing code adjustment reaches 40% -100%;

(10) No flashing at low input voltage.

In this embodiment, specific: the LED constant current driving chip IC comprises a GND pin, an NC pin, a ROVP pin, a DIM pin, an HV pin, a DRAIN pin, a SOURCE pin and a CS pin, the output no-load control circuit comprises a resistor R2, the code pulling switch current adjusting circuit comprises a code pulling switch DIP, the constant current IC control circuit further comprises a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a capacitor C3, and the high-frequency oscillation output circuit comprises a diode D1 and a transformer T1.

Overview of LED constant current drive chip IC

IC2872TS is a non-isolated, step-down LED constant current driving chip specially used for adjusting current of dial switch. When the current is regulated through the dial switch, the OVP voltage is not influenced by the output current gear, and the reliability and the safety of the system are improved. IC2872TS provides four-gear fixed OVP voltage and can be flexibly selected through an external resistor.

The DIM pin of the IC2872TS supports the output current setting by selecting different resistors through a dial switch, and the setting range is 40% -100%. The DIM pin has an enable function, which can be used to switch the tinting or sense light control. If a capacitor is connected in parallel with the DIM pin, a soft start function can be realized.

IC2872TS operates in an inductor current critical continuous mode without the need for auxiliary windings for demagnetization detection. Meanwhile, a high-voltage JFET power supply circuit is integrated in the chip, a VCC capacitor and a starting resistor are not needed, and peripheral components are few and the cost is lower. The IC2872TS is internally provided with a high-precision current sampling circuit, so that high-precision LED constant current output and excellent line voltage adjustment rate and load adjustment rate can be realized.

As shown in fig. 2-3: IC2872TS employs BPSOP packages and internal structural frame diagrams;

1. pin descriptions of IC2872TS chips are shown in the following table:

Pin number	Pin name	Description of the invention
			1，9	GND	Chip ground
2	NC	Connectionless, suspended handling during application
			3	ROVP	OVP voltage selection pin
4	DIM	Current regulating and soft starting pin of beam current dial switch
			5	HV	Chip high-voltage power supply and beam in-voltage detection pin
6，7	DRAIN	Internal high-voltage power tube drain
			8	SOURCE	Internal high voltage power tube source
10	CS	MOSFET current sampling

2. Limiting parameters are shown in the following table:

Sign symbol	Parameters (parameters)	Parameter range	Unit (B)
				HV	High voltage JFET maximum voltage	-0.3～600	V
DRAIN	Peak drain-to-source voltage of internal high voltage power tube	-0.3～500	V
				CS，ROVP，DIM	Chip low-voltage interface	-0.3～7	V
SOURCE	Internal high-voltage power tube drain voltage withstand	-0.3～7	V
				PDMAX	Power consumption (annotate 2)	0.77	W
θJA	Junction to ambient thermal resistance (note 3)	85	℃/W
				TJ	Working junction temperature range	-40～150	℃
TSTG	Storage temperature range	-55～150	℃

As shown in fig. 1, in this embodiment, specifically: the 2 feet of the rectifier bridge DB1 are simultaneously connected with one end of a resistor R1, a capacitor C1, a GND pin of an LED constant current driving chip IC, a resistor R2, a resistor R5, a resistor R6, a resistor R7 and a capacitor C3 respectively, the 3 feet of the rectifier bridge DB1 are also connected with one ends of a diode D1, an LED+ -LED-lamp bead string, a load resistor R3, a capacitor C2 and a resistor R4, the other ends of the LED+ -LED-lamp bead string, the load resistor R3 and the capacitor C2 are connected with one end of a transformer T1, and the other end of the diode D1 is connected with the DRAIN pin of the LED constant current driving chip IC and the other end of the transformer T1 respectively.

As shown in fig. 1, in this embodiment, specifically: the other end of the resistor R1 is connected with the SOURCE pin and the CS pin of the LED constant current driving chip IC, the other end of the resistor R4 is connected with the HV pin of the LED constant current driving chip IC, the other end of the resistor R2 is connected with the ROVP pin of the LED constant current driving chip IC, the other ends of the resistor R6 and the resistor R7 are connected with one end of the DIP switch, and the other ends of the capacitor C1, the DIP switch DIP and the resistor R5 are connected with the DIM pin of the LED constant current driving chip IC.

The electrical characteristics in this embodiment, it should be noted that: typical parameters are parameter criteria measured at ta=25℃; as shown in tables 1 to 3 below:

TABLE 1

TABLE 2

TABLE 3 Table 3

In this embodiment, specific: the fuse wire F1 is a fuse/PTC thermistor.

In this embodiment, specific: the model of the LED constant current driving chip IC is IC2872TS.

Working principle: IC2872TS is a non-isolated, step-down LED constant current driving chip specially used for adjusting current of dial switch. When the current is regulated through the dial switch, the OVP voltage is not influenced by the output current gear, and the reliability and the safety of the system are improved. IC2872TS provides four-gear fixed OVP voltage and can be flexibly selected through an external resistor.

(1): Power supply start

After the system is electrified, the input voltage supplies power to the inside of the chip through the HV pin, and when the internal VDD voltage reaches the chip starting threshold value, the control circuit in the chip starts to work. During normal operation of the chip, the required operating current is still supplied to it via the internal JFET.

(2): Constant current control, output current setting

The chip detects peak current of the inductor cycle by cycle, the CS end is connected to the input end of an internal peak current comparator and is compared with an internal V _CS threshold voltage, and when the CS voltage reaches an internal detection threshold value, the power tube is turned off.

The inductance peak current is expressed as: i _PK＝V_CS÷R_CS

The output of the CS comparator also includes a 350ns leading edge blanking time.

The LED output current calculating method comprises the following steps: i _OUT＝0.5×I_PK

(3): Current regulating function of dial switch

The DIM pin has 20 mu A pull-up current inside, and when the DIM is changed to the ground resistance through the dial switch, the voltage of the DIM pin is correspondingly changed. The DIM pin voltage is limited and then used as a reference voltage for the CS comparator, thereby setting the LED current. The DIM pin also has an enable function. When the DIM voltage is lower than VDIM_EN, the chip stops the switching action. The DIM voltage versus CS comparator reference voltage is shown in fig. 5:

(4): output overvoltage protection selection

The open circuit protection voltage has four options, namely: 135V, 225V, 320V, unlimited, can be set by the resistor of ROVP pins. At start-up, 40 μA of current is pulled up inside the chip. The relationship of ROVP voltage to output OVP voltage is shown as follows:

VROVP	＜0.2V	0.2-0.6V	0.6-1.8V	＞1.8V
					VOVP	135V	225V	320V	No OVP

(5): Power inductor

IC2872TS operates in an inductor current critical mode, when the power transistor is turned on, the current flowing through the power inductor rises from zero, and the on time is: t _ON＝(L×Ipk)÷(V_IN-V_LED)

Wherein L is the inductance; ipk is the peak value of the inductor current; v _IN is the rectified bus voltage; v _LED is the voltage on the output LED.

When the power tube is turned off, the current flowing through the power inductor starts to decrease from the peak value, and after the inductor current decreases to zero, the internal demagnetization detection logic of the chip turns on the power tube again. The turn-off time of the power tube is To _FF＝(L×Ipk)÷V_LED

The inductance value calculation formula of the power inductor is as follows:

L＝V_LED×(V_IN-V_LED)÷F×Ipk×V_IN

Wherein F is the system operating frequency. The system operating frequency of the IC2872TS is related to the input voltage, and when the system operating frequency of the IC2872TS is set, the lowest operating frequency of the system is typically selected to be set when the input voltage is lowest, and when the input voltage is highest, the system operating frequency is also highest.

IC2872TS sets the minimum and maximum off times of the system to 1.3 μs and 450 μs, respectively. As shown by a calculation formula of ToFF, if the inductance is small, the actual demagnetizing time may be smaller than the minimum turn-off time, the system will enter an inductance current interruption mode, and the LED output current will deviate from the design value; when the inductance is large, the actual demagnetizing time may exceed the maximum off time of the chip, and the system enters an inductance current continuous mode, and the output LED current also deviates from the design value. It is important to select an appropriate inductance value.

(6): Protection function

LED short-circuit protection

When the LEDs are short-circuited, the IC2872TS can not detect the demagnetizing signal, and the system works at a low frequency of 2kHz, so that the output short-circuit power consumption can be kept at a low level. After the short-circuit fault is removed, the system can resume normal operation.

LED open circuit protection

When the LED is open, the output voltage will rise. When the output voltage is greater than the no-load voltage selected by ROVP resistor, the chip triggers the fault protection logic and enters a hiccup mode. The hiccup interval is TFAULT _rst. After the open circuit fault is relieved, the system automatically resumes normal operation.

Overheat regulation protection

The IC2872TS detects the temperature of the chip through the over-temperature adjusting circuit, when the temperature exceeds 150 ℃, the chip enters an over-temperature adjusting state, and the output current is gradually reduced, so that the output power and the temperature rise are controlled, the temperature of the chip is controlled to be a certain value, and the reliability of the system is improved.

System PCB design

In designing the IC2872TSPCB, the following guidelines need to be followed:

1) The power ground of the CS current sampling resistor is as short as possible, and is connected to the ground of the bus capacitor by tapping with the ground of the chip and other small signal ground lines. In addition, the heat dissipation of the chip can be enhanced by enlarging the copper laying area of the GND pin.

2) The HV pins are as far from the CS pins and other low voltage pins as the soldering allows.

3) Areas of power loops, such as loop areas of power inductors, power tubes, bus capacitors, and loop areas of power inductors, freewheeling diodes, output capacitors, to reduce EMI emissions.

As shown in fig. 6: the utility model provides a PCB board diagram of a code-pulling current-regulating LED circuit.

Although embodiments of the present utility model have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the utility model, the scope of which is defined in the appended claims and their equivalents.

Claims (6)

1. The utility model provides a code pulling and current adjusting LED circuit, includes live wire input L, zero line input N, insurance circuit F1, lightning protection surge circuit, rectification circuit, filter circuit, constant current IC control circuit, output no-load control circuit, code pulling switch current adjusting circuit, high frequency oscillation output circuit, LED work filter circuit and LED work circuit, its characterized in that: the lightning protection surge circuit comprises a piezoresistor RV1, the rectifying circuit comprises a rectifying bridge pile DB1, the piezoresistor RV1 is connected between a live wire input end L and a zero line input end N, one end of the safety circuit F1 is electrically connected with the live wire input end L, the other end of the safety circuit F1 is respectively connected with one end of the piezoresistor RV1 and 4 pins of the rectifying bridge pile DB1, 1 pin of the rectifying bridge pile DB1 is electrically connected with the zero line input end N, the filtering circuit comprises a capacitor C1, 3 pins of the rectifying bridge pile DB1 of the rectifying circuit are connected with the positive electrode of the capacitor C1, the filtering circuit is respectively connected with a constant current IC control circuit, an output no-load control circuit, an LED working filtering circuit and an LED working circuit, the constant current IC control circuit is respectively connected with the output no-load control circuit, the code pulling switching current control circuit and a high-frequency oscillation output circuit, the LED working filtering circuit is respectively connected with the LED working circuit and the high-frequency oscillation output circuit, the constant current IC control circuit comprises an LED driving chip IC, the LED driving chip comprises an LED lamp, the LED lamp and LED lamp string and the two ends of the LED driving chip comprises an LED string and an LED load R3 and an LED load resistor R2.

2. The code-pulling current-regulating LED circuit of claim 1, wherein: the LED constant current driving chip IC comprises a GND pin, an NC pin, a ROVP pin, a DIM pin, an HV pin, a DRAIN pin, a SOURCE pin and a CS pin, the output no-load control circuit comprises a resistor R2, the code pulling switch current adjusting circuit comprises a code pulling switch DIP, the constant current IC control circuit further comprises a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a capacitor C3, and the high-frequency oscillation output circuit comprises a diode D1 and a transformer T1.

3. The code-pulling current-regulating LED circuit of claim 2, wherein: the 2 feet of the rectifier bridge DB1 are simultaneously connected with one end of a resistor R1, a capacitor C1, a GND pin of an LED constant current driving chip IC, a resistor R2, a resistor R5, a resistor R6, a resistor R7 and a capacitor C3 respectively, the 3 feet of the rectifier bridge DB1 are also connected with one ends of a diode D1, an LED+ -LED-lamp bead string, a load resistor R3, a capacitor C2 and a resistor R4, the other ends of the LED+ -LED-lamp bead string, the load resistor R3 and the capacitor C2 are connected with one end of a transformer T1, and the other end of the diode D1 is connected with the DRAIN pin of the LED constant current driving chip IC and the other end of the transformer T1 respectively.

4. The code-pulling current-regulating LED circuit of claim 2, wherein: the other end of the resistor R1 is connected with the SOURCE pin and the CS pin of the LED constant current driving chip IC, the other end of the resistor R4 is connected with the HV pin of the LED constant current driving chip IC, the other end of the resistor R2 is connected with the ROVP pin of the LED constant current driving chip IC, the other ends of the resistor R6 and the resistor R7 are connected with one end of the DIP switch, and the other ends of the capacitor C1, the DIP switch DIP and the resistor R5 are connected with the DIM pin of the LED constant current driving chip IC.

5. The code-pulling current-regulating LED circuit of claim 1, wherein: the fuse wire F1 is a fuse/PTC thermistor.

6. The code-pulling current-regulating LED circuit of claim 1, wherein: the model of the LED constant current driving chip IC is IC2872TS.