JP2001312316A - Current supply controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the spike-like voltage fluctuation of an output voltage to be supplied to a load when switching a current limit quantity for limiting an output current to the load. SOLUTION: A current supply controller having a current supplying means for supplying a current to a load 11, current limiting means for limiting the value of the current to be supplied to the load 11 by the current supplying means, current detecting means for detecting the current supplied to the load as a voltage value and outputting this detected voltage, comparing means 8 for comparing the detected voltage of the current detecting means with a preset deciding voltage, current regulating means for regulating the current limit quantity in the current limiting means on the basis of the compared result of the comparing means 8, and setting means 1 for supplying a prescribed setting value to each of current supplying means, current limiting means and comparing means 8, is provided with time control means (3F and 10B) for controlling time required for the current regulating means to switch the current limit quantity on the basis of the output of the comparing means 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current supply control device, and more particularly, to a current supply control device suitable for use in a single power supply device and an integrated circuit measuring device.

[0002]

2. Description of the Related Art The configuration of a conventional current supply control device is shown in FIG. In the figure, a current supply control device is a CPU 1
, D / A converters 2A to 2C, resistors 3A to 3F, operational amplifiers 4A and 4B, a transistor 5, a diode 6, a current detection circuit 7, a comparison circuit 8, and a switch 9A.
And a capacitor 10A. 11 is a load.

The CPU 1 is connected to a D / A converter 2A, and the output terminal of the D / A converter 2A is connected via a resistor 3A to an inverting input terminal of an operational amplifier 4A. The non-inverting input terminal of the operational amplifier 4A is grounded. The output terminal of the operational amplifier 4A is connected to a capacitor 10A via a resistor 3C.
Of the capacitor 10A, and the other end of the capacitor 10A is grounded. Capacitor 1
One end of 0A and the load 11 are connected to the inverting input terminal of the operational amplifier 4A via the feedback resistor 3B. Thereby, in the operational amplifier 4A, a negative feedback closed loop is formed in a path from the output terminal to the inverting input terminal.

The operational amplifier 4A has a current limit adjusting terminal A to which the collector terminal of the transistor 5 is connected. In the base of transistor 5,
The output terminal of the operational amplifier 4B is connected, and the output terminal of the D / A converter 2B is connected to the non-inverting input terminal of the operational amplifier 4B. The emitter of the transistor 5 is connected to the negative power supply B via the resistor 3D, and the operational amplifier 4
B is connected to the inverting input terminal of B. Accordingly, a negative feedback closed loop is formed in a path from the output terminal of the operational amplifier 4B to the inverting input terminal of the operational amplifier 4B via the emitter of the transistor 5.

On the other hand, one end of the detection resistor 3C is connected to the output terminal of the operational amplifier 4A, the other end is connected to one end of the capacitor 10A and the load 11, and the other end of the capacitor 10A is grounded. One end and the other end of the detection resistor 3C are connected to the input side of the current detection circuit 7, and the output end of the current detection circuit 7 is connected to one input end of the comparison circuit 8. The other input terminal of the comparison circuit 8 is connected to the CPU 1 via the D / A converter 2C. The collector of the transistor 5 is connected to a negative power supply B via a series circuit of a diode 6 and a resistor 3E. The cathode of the diode 6 is connected to one end of the switch 9A via the resistor 3F, and the other end of the switch 9A is grounded. The output terminal of the comparison circuit 8 is connected to the control terminal of the switch 9A.

Next, the operation of the conventional current supply control device shown in FIG. 2 will be described. The function of this device is
And a current limiting operation for limiting the output current IO of the operational amplifier 4A, and setting the input voltage VIN from the CPU 1 and the load 11
Of supplying the current IO required by the operational amplifier 4A from the operational amplifier 4A. First, a current limiting operation for limiting the output current IO will be described. The CPU 1 sets a voltage for limiting the output current IO of the operational amplifier 4A by a digital signal, and converts the digital signal into an analog signal by the D / A converter 2B. This signal is input to the operational amplifier 4B, causing a potential difference between the base and the emitter of the transistor 5, and a current flows from the base to the emitter. As a result, the transistor 5 operates, and the limiting current IA flowing to the current limiting adjustment terminal A of the operational amplifier 4A is determined by the negative power supply B, the emitter voltage, and the resistor 3D.

Here, assuming that the resistance value of the resistor 3D is RD and the power supply voltage of the negative power supply B is VB, the emitter voltage of the transistor 5 is set by the CPU 1 as a digital value.
Since the voltage is substantially equal to the voltage VC converted into an analog value by the A converter 2B, the limiting current IA flowing to the current limiting adjusting terminal A
Is

(Equation 1) Becomes This limits the current to the operational amplifier 4A so as not to exceed the output current IO excessively.

The output current IO of the operational amplifier 4A and the limit current IA flowing to the current limit adjustment terminal A are:

(Equation 2) There is a relationship. In the equation (2), G is a current amplification factor. The current limiting voltage VC and the output current IO set by the CPU 1 are given by equations (1) and (2).

(Equation 3) Becomes the relationship. In this relational expression, as shown in FIG. 3, the output current IO is proportional to the current limiting voltage VC set by the CPU 1.

An operational amplifier 4A is connected to the detection resistor 3C.
, An output current IO flowing from the output terminal to the load 11 flows, so that a potential difference V1−V2 is generated across the detection resistor 3C. The potential difference is amplified by the current detection circuit 7 and output to one input terminal of the comparison circuit 8 as a detection voltage VRC. The setting of the determination voltage VCL set at the other input terminal of the comparison circuit 8 is performed by comparing and determining whether the current required by the load 11 has been reached. The voltage detected by the current detection circuit 7 is stored in a memory under the control of the CPU 1 in advance. Then, in order for the comparison circuit 8 to make a comparison judgment with the detection voltage VRC, the judgment voltage is set as VCL from the CPU 1 via the D / A converter 2C.

The comparison circuit 8 detects the current immediately before the load 11 reaches the current value required by the potential difference of the detection resistor 3C, and determines the detection voltage VRC amplified by the current detection circuit 7 and the judgment preset by the CPU 1. A comparison is made with the voltage VCL. FIG. 4 shows waveforms of the time t until the load 11 reaches the required current and the detection voltage VRC. FIG. 5 shows the detection voltage V
5 is a waveform showing a current flowing to a current limit adjustment terminal A in an operational amplifier 4A when RC and a determination voltage VCL are compared and determined by a comparison circuit 8; In FIG. 4, a region shorter than the time tr is a state until the current required by the load 11 is reached. Here, since the detection voltage VRC is smaller than the determination voltage VCL set in the comparison circuit 8 from the CPU 1, the switch 9A keeps the OFF state. When the switch 9A is off, a current flows through the diode 6 in the forward bias direction, and a negative power supply B current flows. That is, the operational amplifier 4A
Is IA + IB as shown in FIG.

In the region longer than the time tr in FIG. 4, the current required by the load 11 is reached, and the detection voltage VRC exceeds the determination voltage VCL set by the CPU 1 in the comparison circuit 8, so that the switch 9A is turned on. . Switch 9
When A is in the ON state, conduction is provided between the negative power supply B and the ground, and a current IC flows into the negative power supply B from the ground side due to the potential difference. Assuming that the power supply voltage of the negative power supply B is VB and the resistance values of the resistors 3E and 3F are RE and RF, respectively, the current IC becomes

(Equation 4) Becomes At this time, since the diode 6 is reverse-biased, the current flowing to the negative power supply B is IA + IC. However, the limit current flowing to the current limit adjustment terminal A is only IA as shown in FIG. 5, and the limit current IA initially set by the CPU 1 becomes effective, and the output current IO is limited so as not to flow excessively. .

Next, the operation of supplying a current to the load 11 in response to the setting of the input voltage will be described. In CPU1,
A digital signal corresponding to the input set voltage is set, and D
The digital signal is converted into an analog value by the / A converter 2A. This signal is input to the operational amplifier 4A,
The signal is amplified to the input set voltage by the operational amplifier 4A. The voltage amplified by the operational amplifier 4A is set to the load 11, and the operational amplifier 4A supplies the current IO required by the load 11. At this time, the capacitor 10A is also charged. CPU
The input voltage from 1 is VIN, the resistance of the resistor 3A is R1,
Assuming that the resistance value of the feedback resistor 3B is R2, the voltage value VO applied to the load by the negative feedback closed loop is

(Equation 5) The output voltage VO is determined by the input setting voltage VIN.

Assuming that the capacitance of the capacitor 10A is C, the output current of the operational amplifier 4A is IO, and the output voltage is VO, the time t charged to the capacitor 10A is:

(Equation 6) When the output voltage VO expressed by the equation (5) is substituted into the equation (6), the time t required to charge the capacitor 10A becomes
As shown in the following equation (7), the input voltage VIN and the output current I
It can be seen that the relationship O is established.

[0014]

(Equation 7) When the input voltage VIN is set by the CPU 1, the time t for charging the capacitor 10A depends only on the output current IO. FIG. 6 shows the relationship of Expression (7), and the output current IO and the time t have an inversely proportional relationship. Assuming that the charging current for charging the capacitor 10A is IOC, when the output current IO is smaller than the value of the charging current IOC, a longer charging time for the capacitor 10A is required, and the time t for supplying the current to the load 11 increases.

[0015]

In the conventional current supply control device, when controlling the current limit adjusting terminal A of the operational amplifier 4A, the switch 9A is turned off when the detected voltage value VRC is smaller than the judgment voltage VCL. is there. Operational amplifier 4
When the output current IO of A is supplied to the load 11 and the capacitor 10A, the detection voltage VR detected by the detection resistor 3C
C becomes higher than the determination voltage VCL, and the switch 9A is turned on.

When the switch 9A is switched from the off state to the on state, a reverse bias is applied to the cathode of the diode 6 to control the current IB flowing through the diode 6 and the resistor 3E. At this time, a voltage change is caused by a sudden change in the voltage level, which affects the current limit adjustment terminal A of the operational amplifier 4A, and this influence directly affects the operational amplifier 4A.
As shown in FIG. 8, there is a problem that a slight spike appears in the output voltage VO supplied to the load 11 and the capacitor 10A through the output of A. The present invention has been made in view of such circumstances, and can eliminate a spike-like voltage fluctuation in an output voltage supplied to a load when switching a current limiting amount in order to limit an output current to a load. It is an object to provide a current supply control device.

[0017]

According to one aspect of the present invention, there is provided a current supply means for supplying a current to a load based on a set current value; Current limiting means for limiting a current value supplied to the load by the current supply means based on a value, current detection means for detecting a current supplied to the load as a voltage value, and outputting the detected voltage, A comparing unit that compares a detection voltage of the current detecting unit with a predetermined determination voltage; a current adjusting unit that adjusts a current limiting amount in the current limiting unit based on a comparison result of the comparing unit; A current supply control device having setting means for supplying a predetermined set value to each of a current limiting means and a comparing means, wherein the current adjusting means cuts a current limiting amount based on an output of the comparing means. Characterized in that it has a time adjustment means for adjusting the time required for obtaining.

The invention described in claim 2 is the same as the invention described in claim 1.
In the current supply control device according to the above, the current adjusting means is turned on when the potential between both ends has a specific relationship,
A switching means for switching off the current limiting amount by a switching operation of the switching means; the time adjusting means includes a voltage amplifying means for inverting and amplifying a voltage at one terminal of the switching means; Receiving a voltage applied to the other terminal of the switch so that the switch is switched from an on state to an off state after a predetermined time has passed from the time when the output of the voltage amplifier is received and the output of the voltage amplifier is received. A time-measuring means for gradually increasing the time for switching the switch means from an on-state to an off-state, and the current detecting means provided between an output terminal of the voltage amplifying means and an input terminal of the time-measuring means. The first switch means which is turned on based on the comparison output of the comparison means which is output when the detected voltage of the comparator exceeds a predetermined judgment voltage A comparison output of the comparing means provided between an output terminal of the timing means and the other terminal of the switch means and output when a detection voltage of the current detection means exceeds a predetermined judgment voltage. And a second switch means that is turned on based on

The invention described in claim 3 is the same as the invention in claim 2
In the current supply control device according to the above, the timing means,
A resistor having one end connected to the first switch means and the other end connected to the second switch means, and a capacitor connected between the other end of the resistor and a ground line. And

The invention described in claim 4 is the first invention.
4. The current supply control device according to any one of
A potential state monitoring means for monitoring a potential state between both ends of the switch means and outputting a state signal according to a potential state between both ends of the switch means; and comparing an output signal of the potential state monitoring means with the comparison means. Performs a logical AND operation with the output,
A logic operation means for detecting a power-off state, and a connection point between a resistor constituting the timing means and the first switch means, and a ground line, and And a third switch means that is turned on only when the power is off.

The invention described in claim 5 is the first invention.
The current supply control device according to any one of claims 1 to 4,
The switch means is a diode, and the voltage amplifying means has a function of using the anode voltage of the diode as a reference voltage, inverting the polarity of the reference voltage, and variably amplifying the output side as needed. And

The invention described in claim 6 is the same as the invention in claim 5
Wherein the potential state monitoring means monitors an anode-cathode voltage of the diode, and outputs a state signal according to whether the diode is in a forward bias state or a reverse bias state. It is characterized by outputting.

The invention described in claim 7 is the same as the invention described in claim 2.
Wherein the predetermined time is determined by a time constant, which is a product of a resistance value of a resistor constituting a time determining means and a capacitance value of a capacitor.

According to the first to seventh aspects of the present invention, the current supply means for supplying a current to the load based on the set current value, and the current supply means based on the set current limit value, A current limiter for limiting a current value supplied to the load, a current detector for detecting a current supplied to the load as a voltage value, and outputting the detected voltage, and a detection voltage of the current detector being set in advance. Comparing means for comparing the current with the determined voltage, current adjusting means for adjusting the current limiting amount in the current limiting means based on the result of comparison by the comparing means, and predetermined values for the current supplying means, the current limiting means and the comparing means, respectively. And a setting means for supplying a set value of the current supply control means for adjusting a time required for the current adjustment means to switch the current limit amount based on an output of the comparison means. Since the current adjusting means has an adjusting means, the time adjusting means increases the time required for the current adjusting means to switch the current limiting amount. Specifically, a diode as a switching means for switching the current limiting amount constituting the current adjusting means is provided. By increasing the time until reverse bias is applied to the diode when switching from the on state to the off state, a spike-like voltage fluctuation in the output voltage supplied to the load can be eliminated.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a configuration of a current supply control device according to an embodiment of the present invention. A portion of the current supply control device according to the present embodiment that is different in configuration from the conventional current supply control device shown in FIG. 2 is surrounded by a dotted line in FIG. The same components as those of the current supply control device shown in FIG. 2 are denoted by the same reference numerals.

In FIG. 1, a current supply control device according to the present embodiment supplies a current to a load 11 and a capacitor 10A based on a set current value.
B, 3C and current supply means comprising an operational amplifier 4A;
An operational amplifier 4B for limiting a current value supplied to the load by the current supply means based on the set current limit value;
Current limiting means comprising a transistor 5 and a resistor 3D;
A current detecting means for detecting a current supplied to the load 11 as a voltage value and outputting the detected voltage, the detecting means comprising a detecting resistor 3C and a current detecting circuit 7, and a detection voltage VRC of the current detecting means.
Is compared with a predetermined determination voltage VCL, and a current adjusting means including a diode 6 and a resistor 3E for adjusting a current limiting amount in the current limiting means based on a comparison result of the comparing means. A CPU 1 as setting means for supplying a predetermined set value to each of the current supply means, the current limiting means, and the comparing means;
It has converters 2A, 2B and 2C.

The current adjusting means includes a diode 6 as a switching means for turning on and off when the potential between both ends is in a specific relationship, and the current limiting amount can be switched by the switching operation of the diode. I have.

The voltage inverting amplifier circuit 13 as voltage amplifying means for inverting and amplifying the voltage VA at the anode, which is one terminal of the diode 6, receives the output of the voltage inverting amplifier circuit 13 and receives the output of the voltage inverting amplifier circuit 13. The voltage VK applied to the cathode, which is the other terminal of the diode 6, is gradually increased so that the diode 6 is switched from the on-state to the off-state after a lapse of a predetermined time from the time when the diode 6 is switched from the on-state to the off-state. And a detection voltage VRC of the current detection circuit 7 which is provided between an output terminal of the voltage inverting amplifier circuit 13 and an input terminal of the timing device, and which is set in advance. The first switch means that is turned on based on the comparison output of the comparison circuit 8 that is output when the voltage exceeds the determination voltage VCL Switch 9B and the determination voltage detection voltage VRC of provided current detection circuit 7 is set in advance between the cathode of the output terminal and the diode 6 for time constant means VCL
The current adjusting means switches the current limiting amount based on the output of the comparison circuit 8 by the switch 9A as the second switching means which is turned on based on the comparison output of the comparison circuit 8 which is output when the current exceeds the threshold. Time adjusting means for adjusting the time required for the operation.

The current supply control device according to the present embodiment monitors the potential state between both ends of the diode 6 and outputs a state signal according to the potential state between both ends of the diode 6. 3I, a logical operation for performing a logical product operation of an output signal of the potential state monitoring device and a comparison output of the comparison circuit 8 to detect a power-off state of the current supply control device. Means as a means, and a resistor 3F constituting a timing means.
Switch 9C, which is connected between the connection point between the switch 9B and the switch 9B and the ground line, and which is turned on only when the power is off based on the output signal of the NAND gate 14, I have.

In FIG. 1, a description will be given of a portion added to the current supply control device shown in FIG. 2, that is, a configuration and an operation of a main portion of the present invention. In the figure, B is a negative power supply, and C is a positive power supply. The input terminal of the voltage inverting amplifier 13 is connected to the anode of the diode 6, and the output terminal of the voltage inverting amplifier 13 is connected to one end of the switch 9B. The other end of the switch 9B is connected to one end of the resistor 3F and one end of the switch 9C. The other end of the switch 9C is grounded. One end of the switch 9A is connected to the cathode of the diode 6, and the other end of the switch 9A is connected to one end of the capacitor 10B and the other end of the resistor 3F.

The other end of the capacitor 10B is grounded. The control terminals of the switches 9A and 9B are connected to the output terminal of the comparison circuit 8. These circuits include a diode 6
, And operates with a potential difference (VA−VK) between the anode and the cathode of the diode 6.
The non-inverting input terminal of the comparator 12 has a resistance of 3H.
Is connected to one end of the resistor 3I, and the other end of the resistor 3H is connected to the anode of the diode 6. The inverting input terminal of the comparator 12 is connected to one end of the resistor 3G,
The other end is connected to the cathode of the diode 6.

In the comparator 12, the anode voltage VA based on the non-inverting input terminal of the comparator 12 is used.
And the cathode voltage VK of the diode input from the inverting input terminal to determine the output level. The output terminal of the comparator 12 is connected to one input terminal of the NAND gate 14 and one end of the resistor 3J, and further to the other end of the resistor 3I. The other end of the resistor 3J is connected to the positive power supply C. The other input terminal of the NAND gate 14 is connected to the output terminal of the comparison circuit 8.

The operation of the circuit surrounded by the dotted line in FIG. 1 involves the same operation as that of the conventional current supply control device shown in FIG. The voltage limiting terminal A of the operational amplifier 4A is
When the current limit set by the CPU 1 is not applied, the current IB flows from the voltage limit terminal A to the negative power supply B, and the potential difference (VA-VK) between the anode and the cathode of the diode 6.
Has occurred. At this point, the circuit surrounded by the dotted line in FIG. 1 does not operate at all. When the output current IO is supplied to the load 11 and the capacitor 10A, and a potential difference (V1−V2) is generated between both ends of the detection resistor 3C, the potential difference is amplified by the current detection circuit 7, and is converted to one of the comparison circuits 8 as the detection voltage VRC. Output to the input terminal. In the comparison circuit 8, the detection voltage VR
C is compared with the determination voltage VCL set by the CPU 1, and the determination result is output as a voltage level.

An on / off signal is output to the control terminals of the switches 9A, 9B and 9C according to the result determined by the comparison circuit 8. The anode voltage VA of the diode 6 is input to the voltage inverting amplifier 13 and is converted and amplified by the voltage inverting amplifier 13 to a positive voltage VAR equal to or higher than the anode voltage VA of the diode 6. Hereinafter, this voltage is referred to as a response voltage VAR. Through this voltage inverting amplifier circuit 13, the response voltage VA
The reason for converting to R is that the anode voltage V
Since A is a negative voltage, the anode voltage V
When the potential difference between A and the power supply voltage of the negative power supply B is reversed, that is, when the switches 9A and 9B are in the on state, the negative power supply B is suddenly short-circuited or the voltage supply is stopped. This is to prevent a reverse current from flowing by causing a potential difference between the negative power supply B in the state and the anode voltage VA of the diode 6.

Further, in this voltage inverting amplifier circuit 13, the voltage output from the voltage inverting amplifier circuit 13 is changed only by setting the input voltage as the anode voltage VA of the diode 6. by. Here, the voltage VAR must be higher than the anode voltage VA so as to apply a reverse bias to the diode 6. The response voltage VAR is applied to one end of the switch 9B. When the switch 9B is turned on, the response voltage VAR starts to gradually charge the capacitor 10B through the resistor 3F. At this time, a current also flows to the resistor 3E via the switch 9A,
It reaches the negative power supply B. That is, the comparison circuit 8 uses the switch 9
When A and 9B are turned on, a current path from the response voltage VAR to the negative power supply B is formed.

The cathode voltage VK of the diode 6 is determined by the response voltage VAR, the voltage VB of the negative power supply B, and the voltage dividing ratio of the resistors 3F and 3E provided therebetween. Assuming that the capacitor 10B is sufficiently charged, the cathode voltage VK of the diode 6 is obtained by the following equation.

(Equation 8) The time setting circuit constituted by the resistor 3F and the capacitor 10B forms an integration circuit generally called, and the response voltage V
While charging the capacitor 10B from AR to the cathode of the diode 6 through the resistor 3F, the response voltage VA
It operates to supply a voltage up to the voltage level of R. This operation is transient and non-linear. In the state before reaching the voltage VK, the voltage changes from OV to VAR as shown in FIG.

Assuming that the capacitance of the capacitor 10B is CB and the elapsed time is T, the cathode voltage VK of the diode 6 can be expressed by the following equation.

(Equation 9) Further, the cathode voltage VK of the diode 6 becomes the response voltage VA.
The time T to reach R depends on the resistance 3F forming the integrating circuit.
Is determined by the time constant TA determined by the resistance value RF and the capacitance CB of the capacitor 10B.

(Equation 10) In the circuit added in the present embodiment, a current path flowing from the anode of the diode 6 to the negative power supply B is separately prepared in order to control the current IB flowing from the anode of the diode 6 to the negative power supply B. Is increased, the potential difference between the anode and the cathode of the diode 6 (V
A-VK) is reversed, so that the limiting current IA of the operational amplifier 4A is enabled, and the output current IO flowing to the load 11 and the capacitor 10B can be limited.

In this circuit, the potential difference (VA-VK) between the anode and the cathode of the diode 6 is constantly monitored by using the comparator 12. Comparator 12
The anode voltage VA of the diode 6 is used as a reference voltage, compared with the cathode voltage VK of the diode 6, and the comparison result is output as a voltage level. When the anode voltage VA is lower than the cathode voltage VK, the output of the comparator 12 outputs a high level (H) signal. Also, the anode voltage VA
Is low level (L) when is higher than the cathode voltage VK.
The signal of is output. The AND operation of the voltage level of the comparator 12 and the output level of the comparison circuit 8 is performed by the NAND gate 14, and the switch 9
The on / off state of C is controlled.

The operation of the comparator 12 including the circuit operation will be specifically described.
In other words, when the current required by the load 11 and the capacitor 10A is not flowing, the anode of the diode 6
A potential difference (VA-VK) occurs between the cathodes. At this time, the current IB is supplied from the anode of the diode 6 to the negative power supply B.
And the current limiting terminal A of the operational amplifier 4A is disabled. On the other hand, the comparator 12 calculates the voltage between the anode and the cathode of the diode 6 (VA-VK).
The output voltage level becomes H. The switch 9C is turned on at this time, and the charge charged in the capacitor 10B flows to the ground (GND) by opening the path to the ground (FIG. 10).

When the output level of the comparison circuit 8 is L,
That is, when the current required by the load 11 and the capacitor 10A is flowing, the capacitor 10B has just started to be charged via the resistor 3F, and when the anode-cathode of the diode 6 is in the forward bias state, the comparator 12
Becomes H (FIG. 10). Thereafter, when the capacitor 10B is sufficiently charged, a reverse bias state is established between the anode and the cathode of the diode 6. As a result, the current IB does not flow, the current limiting terminal A of the operational amplifier 4A becomes valid, and the output current IO is limited. Further, the output voltage level of the comparator 12 becomes L. Furthermore,
If a sufficient time has elapsed since the output current IO of the operational amplifier 4A was supplied to the load 11 and the capacitor 10A, the output level of the comparison circuit 8 continues to hold L, and the output level of the comparator 12 also becomes L. (FIG. 10).

In order to terminate the supply of the output current IO from the operational amplifier 4A to the load 10 and the capacitor 10A, termination control is performed by the CPU 1. Then, the potential difference (V1-V2) between both ends of the detection resistor 3C becomes small, and the output level of the comparison circuit 8 becomes H again. As a result, the switches 9A, 9B, 9C are turned off. At this time, the output voltage level of the comparator 12 is slightly low level (L).
Is switched to a high level (H) due to the forward bias between the anode and the cathode of the diode 6 (FIG. 10). The switch 9C is turned on only when the charge of the capacitor 10B is discharged at the start and end of the operation of the current supply control device.
With the addition of these functions, the switch 9A,
Even if the switch 9B is turned off, the charging voltage of the capacitor 10B, that is, the response voltage VAR is maintained without being discharged, so that as soon as the switches 9A and 9B are turned on, it is possible to return to the state before the switch was turned off. it can.

Next, the overall operation of the current supply control device according to this embodiment will be described. In FIG. 1, first,
To limit the output current IO of the operational amplifier 4A, CP
U1 outputs the voltage limiting output current IO to D / A converter 2
Set a digital value to B. The D / A converter 2B converts the digital value into an analog voltage value VC, inputs the digital value to the operational amplifier 4B as the voltage VC, and sets a current limit to the current limit adjustment terminal A of the operational amplifier 4A as the current IA. As a result, the current is limited so that the output current IO does not excessively exceed the operational amplifier 4A.

The setting of the judgment voltage VCL in the comparison circuit 8 is given as a digital value from the CPU 1, and this digital value is converted into an analog value VCL by the D / A converter 2C and set to the other end of the comparison circuit 8. . The input voltage is input as a digital value by the CPU 1, converted into an analog value VIN by the D / A converter 2 A, and set to the load 11. Then, the operational amplifier 4A operates to supply the current required by the load 11. Since the output current IO of the operational amplifier 4A flows to the load 11 through the detection resistor 3C, a potential difference (V1−V2) is generated between both ends of the detection resistor 3C. This potential difference is amplified by the current detection circuit 7 and input to the comparison circuit 8 as the detection voltage VRC.

The detection voltage VRC is compared with the judgment voltage VCL by the comparison circuit 8 and the switch 9 is determined based on the comparison result.
A and 9B are controlled. The detection voltage VRC is equal to the judgment voltage VC.
If it is smaller than L, the switches 9A and 9B continue to be in the off state, so that a forward bias state is established between the anode and cathode of the diode 6, and a current flows through the resistor 3E. That is, the current flowing to the current limit adjustment terminal A of the operational amplifier 4A becomes (IA + IB), and the output current IO can flow more than the current set by the limit current of the limit current IA. At this time, the limiting current IA behaves like a constant current, and the output current IO of the operational amplifier 4A can be determined by the current value IB flowing through the resistor 3E. This current value I
B depends only on the resistance value of the resistor 3E, so that the resistor 3B can output the maximum current of the operational amplifier 4A.
If the resistance value of E is determined, the load 11 and the capacitor 1
0 can supply the current required, and the current can be supplied with the maximum current driving capability of the operational amplifier 4A.

When the detection voltage VRC becomes higher than the determination voltage VCL, the switches 9A and 9B are turned on. The anode voltage VA of the diode 6 is inverted and amplified by the voltage inverting amplifier circuit 13 to become the response voltage VAR. The response voltage VAR is applied to the capacitor 10B via the resistor 3F, and the capacitor 10B starts charging. After a lapse of time CB / RF from the charging start time, the diode 6
Because a reverse bias is applied between the anode and cathode of
The current IB stops flowing. As a result, the current flowing from the current limit adjustment terminal A of the operational amplifier 4A to the negative power supply B is only the limited current IA, and the operational amplifier 4A operates to limit the output current IO.

The response voltage VAR is supplied to the cathode of the diode 6 via a time-setting circuit (integrating circuit) composed of the resistor 3F and the capacitor 10B, so that a reverse bias voltage is applied between the anode and the cathode of the diode 6. By slowing the time until the application, the current flowing from the current adjustment terminal A of the operational amplifier 4A to the negative power supply B is controlled from IB to IA, and the current is limited to the output current IO flowing to the load 11 and the capacitor 10A. I try not to affect the time. By these operations, the output current IO supplied to the load 11 and the capacitor 10 is smaller than that of the conventional device.
It takes time to control the current limit adjustment terminal A of the operational amplifier 4A. This is because the capacitor 10B is being charged. However, when limiting the output current IO, it is possible to eliminate the influence of a slight spike generated when the switch is switched.

The overall flow of the operation of the current supply control device is as follows:
It is as shown in FIG. FIG. 10 is a flowchart showing the operation state of the circuit surrounded by the dotted line in FIG. FIG. 11 is an explanatory diagram showing an operation state of each unit of the current supply control device shown in FIG. In the conventional device, when the switch is turned on, a reverse bias is instantaneously applied between the anode and the cathode of the diode 6, so that the voltage of the current limit adjustment terminal A fluctuates rapidly, and the transient voltage is applied to the output terminal of the operational amplifier 4A. Although a fluctuation was observed, in the current supply control device according to the present embodiment, since the reverse bias was slowly applied between the anode and the cathode of the diode 6, the voltage of the current limit adjustment terminal A also switched slowly, so that the operational amplifier The output of 4A is not affected.

According to the embodiment of the present invention, when the setting of the limiting current IA to the operational amplifier 4A is made effective, the switch 9
By slightly increasing the time for applying a reverse bias to the diode 6 after A and 9B are turned on,
Sudden voltage fluctuations occurring at the current limit adjustment terminal A of the operational amplifier 4A can be alleviated, slow voltage switching can be performed, and slight spike-like voltage fluctuations generated at the time of switch switching can be eliminated. .

[0049]

According to the present invention as described above,
A current supply unit that supplies a current to a load based on a set current value; a current limit unit that limits a current value supplied to the load by the current supply unit based on a set current limit value; Current detection means for detecting the current supplied to the power supply as a voltage value and outputting the detected voltage, a comparison means for comparing the detection voltage of the current detection means with a predetermined judgment voltage, and a comparison result of the comparison means A current adjusting unit that adjusts a current limiting amount in the current limiting unit based on the current supply unit, and a setting unit that supplies a predetermined set value to each of the current supplying unit, the current limiting unit, and the comparing unit. There is provided a time adjusting means for adjusting a time required for the current adjusting means to switch the current limiting amount based on an output of the comparing means. By increasing the time required for the regulating means to switch the current limiting amount, specifically, when switching the diode as the switching means for switching the current limiting amount constituting the current regulating means from the on state to the off state, the diode is switched to the off state. By increasing the time until the reverse bias is applied, a spike-like voltage fluctuation in the output voltage supplied to the load can be eliminated.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a current supply control device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a conventional current supply control device.

FIG. 3 is a characteristic diagram showing a relationship between a current limiting voltage VC set by a CPU and an output current IO in the current supply control device.

FIG. 4 is a characteristic diagram showing a relationship between a time t until a load reaches a required current and a detection voltage VRC.

FIG. 5 is a characteristic diagram showing a relationship between a detection voltage VRC and an output current IO.

FIG. 6 is a characteristic diagram showing a relationship between a charging time t of a capacitor and an output current in a time setting circuit.

FIG. 7 shows a cathode voltage VK of the diode in FIG.
FIG. 5 is a characteristic diagram showing a relationship between a cathode voltage VK and an elapsed time T.

FIG. 8 is a diagram showing a waveform of an output voltage VO when a switch is switched between the current supply control device according to the present embodiment and a conventional current supply control device.

FIG. 9 is a diagram showing the overall flow of the operation of the current supply control device according to the embodiment shown in FIG. 1;

FIG. 10 is a diagram showing a flow of operation of a circuit surrounded by a dotted line in FIG. 9;

11 is an explanatory diagram showing an operation state of each unit of the current supply control device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2A-2C D / A converter 3A-3J Resistance 4A-4B Operational amplifier 5 Transistor 6 Diode 7 Current detection circuit 8 Comparison circuit 9A-9C Switch 10A-10B Capacitor 11 Load

Claims (7)

[Claims] A current supply unit that supplies a current to a load based on a set current value; and a current limit that limits a current value supplied to the load by the current supply unit based on a set current limit value. Means, a current detecting means for detecting a current supplied to the load as a voltage value, and outputting the detected voltage; a comparing means for comparing a detection voltage of the current detecting means with a predetermined determination voltage; A current adjusting unit that adjusts a current limiting amount in the current limiting unit based on a comparison result of the comparing unit; and a current supply unit, a current limiting unit, and a comparing unit, respectively.
A current supply control device having setting means for supplying a predetermined set value, comprising: a time adjusting means for adjusting a time required for the current adjusting means to switch the current limiting amount based on an output of the comparing means. A current supply control device characterized by the above-mentioned. 2. The current adjusting means includes switch means for turning on and off when a potential between both ends is in a specific relationship, and a current limiting amount can be switched by a switching operation of the switch means. The time adjusting means includes a voltage amplifying means for inverting and amplifying a voltage at one terminal of the switch means; and A timing means for gradually increasing the voltage applied to the other terminal of the switch means so as to switch the switch means from the on state to the off state, and adjusting a time for switching the switch means from the on state to the off state; The detection voltage of the current detection means provided between the output terminal of the voltage amplification means and the input terminal of the timing means exceeds a predetermined determination voltage. A first switch that is turned on based on a comparison output of the comparison means that is output when the current detection is performed. The first switch is provided between an output terminal of the timing means and the other terminal of the switch. And a second switch unit that is turned on based on a comparison output of the comparison unit that is output when a detection voltage of the unit exceeds a predetermined determination voltage. The current supply control device according to any one of the preceding claims. 3. The timing means includes a resistor having one end connected to the first switch means and the other end connected to the second switch means, and a resistor connected between the other end of the resistor and a ground line. The current supply control device according to claim 2, further comprising a capacitor connected to the current supply control device. 4. A potential state monitoring means for monitoring a potential state between both ends of the switch means and outputting a state signal according to a potential state between both ends of the switch means, and an output signal of the potential state monitoring means. A logical operation unit that performs a logical product operation with the comparison output of the comparison unit to detect a power-off state; and a connection between a resistor that forms the timing unit and the first switch unit and a ground line. And a third switch unit that is turned on only when in a power-off state based on an output signal of the AND operation unit, and that is connected to the third switch unit. Current supply control device. 5. The switch means is a diode, and the voltage amplifying means uses the anode voltage of the diode as a reference voltage, inverts the polarity of the reference voltage, and variably amplifies the output side as necessary. The current supply control device according to any one of claims 1 to 4, further comprising: 6. The potential state monitoring means monitors a voltage between an anode and a cathode of the diode, and outputs a state signal according to whether the diode is in a forward bias state or a reverse bias state. Claim 5
3. The current supply control device according to claim 1. 7. The current supply control device according to claim 2, wherein the predetermined time is determined by a time constant which is a product of a resistance value of a resistor and a capacitance value of a capacitor constituting the time-fixing means. .