JPH08331758A - Voltage comparing type current control circuit and overcurrent limiting circuit - Google Patents

Abstract

PURPOSE: To prevent oscillation of an overcurrent limiting circuit by a method wherein an output current of a power transistor drive circuit is extracted and thereby a feedback control is conducted so that a power transistor may be brought into an off-state in an overcurrent. CONSTITUTION: When a load impedance lowers as is the case with short- circuiting of a load and an output current of power FET (transistor) 10 and a current thereof for detection increase and when the current for detection exceeds a reference current (i.e., in an overcurrent), a minute potential difference occurs between an input voltage Vin from a resistance element 21 and a reference voltage Vref. Here, most of a current (a current corresponding to the overcurrent) flowing to a transistor Q2 outputting the reference current Vref, out of transistors Q1 and Q2 forming a differential couple, is outputted as a base current of an NPN transistor 23 for output, the NPN transistor 23 for output extracts an output current of a power FET drive circuit and thereby conducts a feedback control so that the power FET 10 may be brought into an off-state, and thereby the power FET 10 is protected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage comparison type current control circuit and an overcurrent limiting circuit using the same, and more particularly to a bipolar type voltage comparison type current control circuit for detecting a minute potential difference which operates at a low voltage level. And an overcurrent limiting circuit for detecting and protecting an overcurrent of a semiconductor device using the same, for example, an overcurrent limiting circuit formed on the same chip as a voltage-driven power transistor having a multi-cell structure Used for.

[0002]

2. Description of the Related Art FIG. 4 shows a power M formed in an integrated circuit.
A conventional example of an overcurrent limiting circuit of an OSFET (insulated gate type field effect transistor) is shown. In FIG. 4, 10
Is a DMOS (double diffusion type) power FE having a multi-source structure (first source 10a, second source 10b)
The drain is T, and its drain is connected to the power supply terminal 20 and the first source (current output terminal) 10a is connected to the current output terminal (external load connection terminal) 11 of the IC. Reference numeral 12 is a load circuit connected to the current output terminal 11.

Reference numeral 13 indicates a power F from a built-in current source 13a.
This is a power FET drive circuit for controlling the gate potential of the power FET by turning on / off the supply output of the charging current to the gate capacitance C of the ET according to the power FET drive control signal.

Reference numeral 21 is connected to the second source (current detection terminal) 10b of the power FET, and the current detection terminal 1 is connected.
It is a resistance element that converts a current flowing through 0b into a voltage signal and outputs the voltage signal.

An output 22 from the resistance element 21 is input to 22 and this input voltage is compared with a predetermined reference voltage Vref. When the input voltage becomes larger than the reference voltage (for detecting the current flowing to the current detecting terminal 10b). This is a linear type voltage comparison circuit that outputs a current according to the overcurrent (when the current is overcurrent).

Reference numeral 23 denotes an output NPN transistor to which the output current of the voltage comparison circuit 22 is given as a base current, and the power FE is provided between the collector and the emitter thereof.
It is connected between the output node of the T drive circuit 13 and the ground node.

The voltage comparison circuit 22 and the output transistor 23 detect the overcurrent of the power FET,
The power FET is driven by drawing the output current of the power FET drive circuit 13 according to the overcurrent and flowing it to the ground potential.
Voltage comparison type current control circuit 2 for controlling gate potential of 10
Make up 4.

In order to reduce the influence of the potential fluctuation on the current detection terminal 10b of the power FET, which is caused by the voltage drop generated in the resistance element 21, the resistance value of the resistance element 21 is relatively small, and the voltage drops are compared. It is set to be small.

Therefore, the voltage comparison circuit 22 needs to operate at a low voltage level in order to compare the voltage drop generated in the resistance element 21 with the reference voltage Vref and detect a minute potential difference between the two. , Bipolar transistors are used.

Further, the output NPN transistor 2
Since No. 3 is driven by the output of the voltage comparison circuit 22 which operates at a low voltage level, a bipolar transistor is used in which the variation in the base-emitter voltage is smaller than the variation in the threshold voltage of the MOS transistor. Further, the output NPN transistor 23 has a power F
Since a large collector current flows when the output current of the ET drive circuit 13 is extracted and supplied to the ground potential, a relatively large current also flows to its base.

Next, the structure and operation of the conventional voltage comparison circuit 22 will be described. The voltage comparison circuit 22 is supplied with an input voltage Vin and a predetermined reference voltage Vref corresponding to respective bases, and has a PNP first transistor Q1 whose emitters are directly connected to each other so as to form a differential pair. And a second transistor Q2, and a constant current source 25 connected between the emitter common connection node of the transistors Q1 and Q2 forming the differential pair and the first power supply potential (power supply potential Vcc on the high potential side). , An NPN type in which the collector and the emitter are connected between the collector of the first transistor Q1 and the second power supply potential (the power supply potential on the low potential side, the ground potential Vss) and the collector and the base are connected to each other. A third transistor Q3 and a collector of the second transistor Q2
Of the NPN-type fourth transistor Q4, the emitter of which is connected to the ground potential Vss and the base of which is connected to the base of the third transistor Q3. The third transistor Q3 and the fourth transistor Q4 form a current mirror circuit.

In the operation of the voltage comparison circuit 22, when the input voltage Vin is equal to the reference voltage Vref, the same current flows through the transistors Q1 and Q2 forming the differential pair, so that the output current from the voltage comparison circuit 22 is not generated. On the contrary,
When the input voltage Vin is higher than the reference voltage Vref, the currents of the transistors Q1 and Q2 forming a differential pair correspondingly decrease and increase. At this time, the transistors Q3 and Q4 of the current mirror circuit decrease, and a difference current between the current flowing through the transistor Q2 and the current flowing through the transistor Q4 (current corresponding to the overcurrent) is output.

Next, the operation of the overcurrent limiting circuit having the above configuration will be described. During normal operation, the impedance of the load circuit 12 is, for example, 12Ω, the voltage applied to the power supply terminal 20 is, for example, 12V, and the pulse signal input of the power FET drive circuit 13 is changed between 0V and 5V, for example, and the pulse signal output is obtained. Changes between 0V and, for example, 20V. At this time, when 20V is applied to the gate of the power FET 10, 1 is output from the current output terminal 10a of the power FET.
A flows, and a current of about 1/1000 (about 1 mA) flows to the current detection terminal 10b of the power FET 10.

In this state, the input voltage Vin is the reference voltage V
Since a current equal to ref and equal to the transistors Q1 and Q2 forming the differential pair in the voltage comparison circuit 22 flows, an output current from the voltage comparison circuit 22 does not occur.

Then, when the load impedance is lowered, such as when the load is short-circuited, the output current of the power FET 10 and the detection current increase, and the detection current exceeds the reference current (overcurrent), the resistance element 21 A minute potential difference is generated between the input voltage Vin and the reference voltage Vref in the direction in which the input voltage Vin is slightly higher than the reference voltage Vref. As a result, the output NPN transistor 23, to which the output current of the voltage comparison circuit 22 is given as the base current, becomes the power FE.
Power FET 1 by pulling out the output current of T drive circuit 13
The power FET 10 is protected by performing feedback control so that 0 is turned off.

However, since the voltage comparison circuit 22 having the above-described structure has a large operation gain, the output voltage is sharply inverted according to the magnitude relationship between the input voltage Vin and the reference voltage Vref, and the input voltage V
When in becomes larger than the reference voltage Vref, the transistors Q1 and Q2 forming a differential pair are rapidly turned off and turned on. Such an operation is not suitable for linearly controlling the output current, and the voltage comparison circuit 2 having the above configuration is not suitable.
In the overcurrent limiting circuit including 2, the control operation becomes unstable,
It may oscillate.

FIG. 5 shows that the power supply voltage is applied to the power supply terminal 20 when the load is short-circuited in the circuit of FIG.
It shows how the waveform of the drain-source current IDS of the power FET 10 becomes unstable when the control operation of the T feedback control path becomes unstable and the overcurrent limiting circuit oscillates.

FIG. 6 shows another conventional example of an overcurrent limiting circuit for a power MOSFET. This overcurrent limiting circuit is shown in FIG.
Compared with the overcurrent limiting circuit shown in FIG.
4 and the other parts are the same, and are therefore assigned the same reference numerals as in FIG. In the voltage comparison circuit 22a, the emitters of the transistors Q1 and Q2 forming a differential pair are shared by the voltage comparison circuit 22 shown in FIG. It is modified to connect to the connection node.

However, since the voltage comparison circuit 22a has the active load elements Q3 and Q4 of the current mirror configuration, the operating gain thereof is still relatively large, so that the control operation of the overcurrent limiting circuit is unstable as described above. And the problem of oscillation remains.

In the voltage comparison circuit 22a, when the input voltage Vin becomes larger than the reference voltage Vref, a relatively large base current flows from the transistor Q2 to the output NPN transistor 23, and the input voltage Vin becomes the reference voltage Vref.
When equal to ref, a current equal to the base current flows through the transistors Q3 and Q4 of the current mirror circuit. Thus, when the input voltage Vin is equal to the reference voltage Vref, an extra current flows through the transistor Q1 by the base current of the transistors Q3 and Q4 rather than the transistor Q2. Therefore, the voltage comparison circuit 22a has a large input voltage offset when the input voltage Vin is equal to the reference voltage Vref (when the output is inverted), and is applied to the minute potential difference detection circuit used in the overcurrent limiting circuit of the power MOSFET. Is not suitable.

[0021]

As described above, the conventional voltage comparison type current control circuit is not suitable for linearly controlling the output current because its operating gain is relatively large. When applied to a limiting circuit, there is a problem that oscillation may occur during feedback control when an overcurrent of the protected element is detected.

Further, when the input voltage is equal to the reference voltage, a current commensurate with a relatively large base current of the output transistor is passed through the current mirror load, so that the input voltage offset at the time of output reversal becomes large, and a small potential difference detection circuit is provided. There was a problem that the application was inappropriate.

The present invention has been made to solve the above-mentioned problems, and has a relatively small operating gain, is capable of linearly controlling an output current, has a small input voltage offset at the time of output inversion, and has a small amount. An object is to provide a voltage comparison type current control circuit which can be applied to a potential difference detection circuit. Another object of the present invention is to provide an overcurrent limiting circuit capable of preventing oscillation when detecting an overcurrent of a protected semiconductor element and performing feedback control.

[0024]

The voltage comparison type current control circuit of the present invention is provided with an input voltage and a reference voltage corresponding to respective bases, has the same polarity of bipolar type, and has a differential pair. A first transistor and a second transistor which are connected to each other, and a first transistor and a second transistor which form the differential pair, and are connected between an emitter common connection node and a first power supply potential. A constant current source, a collector of the first transistor and a second
The collector and emitter are connected to the power supply potential of
A bipolar-type third transistor having a collector and a base connected to each other and having a polarity opposite to that of the first transistor, and a third transistor having the same polarity as the third transistor, the collector of which is the collector of the second transistor. A bipolar-type fourth transistor whose emitter is connected to the second power supply potential, and a first transistor connected between the collector of the fourth transistor and the base of the third transistor. And a second resistance element connected between the base of the fourth transistor and the base of the third transistor, the second resistance element having the same polarity as that of the fourth transistor, and the base thereof is A bipolar transistor connected to the collector of the fourth transistor, a current source connected to the collector, and an emitter connected to the second power supply potential. Characterized by comprising a fifth transistor for current control.

The overcurrent limiting circuit of the present invention includes a voltage-driven power transistor having a multi-cell structure,
A power transistor drive circuit for controlling the control electrode potential of the power transistor by on / off controlling the supply output of the charging current to the control electrode capacitance of the power transistor according to the drive control signal for the power transistor, A current-voltage conversion resistance element that causes a voltage drop corresponding to a detection current flowing through a current detection terminal of the power transistor, and the current-voltage conversion resistance element that has the same configuration as the voltage comparison type current control circuit. The generated voltage is applied as the input voltage, and the collector of the fifth transistor for current control is connected between the output node of the power transistor drive circuit and the second power supply potential. The overcurrent of the detection current flowing through the current detection terminal of is detected, and the detected overcurrent is detected. Characterized by comprising a voltage comparison type current control circuit for controlling the control electrode potential of the power transistor by pulling out the output current of the power transistor drive circuit.

[0026]

In the voltage comparison type current control circuit of the present invention, when the input voltage is equal to the reference voltage, the same current flows through the transistors forming the differential pair, so that no output current is generated. In this state, the same current flows through the transistors forming the differential pair, so that no output current is generated. At this time, a current flows from the first transistor of the transistors forming the differential pair to the base of the transistor of the current mirror circuit, and the second transistor of the transistors forming the differential pair forms the base of the transistor of the current mirror circuit. The input voltage offset is small because a current flows through it.

On the other hand, when the input voltage of the voltage comparison type current control circuit is larger than the reference voltage, the current of the first transistor of the transistors forming the differential pair decreases and the current of the second transistor decreases. Increase. At this time, the current of the transistor connected in the current mirror decreases, and most of the current flowing in the second transistor (current corresponding to the overcurrent) is output as the base current of the output transistor, and the output transistor is output. An electric current flows according to the overcurrent. At this time, since the resistance element is connected to the current-mirror connected transistor, the operation gain of the voltage comparison type current control circuit is relatively small, and the output current can be linearly controlled.

In the overcurrent limiting circuit of the present invention, during normal operation, the input voltage is equal to the reference voltage, and the same current flows through the transistors forming the differential pair in the voltage comparison type current control circuit, so that no output current is generated, The output transistor is off.

On the other hand, when the load impedance of the power transistor decreases, the output current of the power transistor increases, and when the current for current detection exceeds the reference current (overcurrent), voltage comparison type current control The input voltage of the circuit becomes larger than the reference voltage, and the output current of the power transistor drive circuit is extracted to perform feedback control so that the power transistor is turned off, thereby protecting the power transistor. At this time, since the gain of the voltage comparison type current control circuit included in the power transistor feedback control path is relatively low, the operation when feedback control is performed by detecting the overcurrent of the power transistor does not become unstable, and the overcurrent limit It becomes possible to prevent oscillation of the circuit.

[0030]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a voltage comparison type current control circuit and an overcurrent limiting circuit using the same according to one embodiment of the present invention.

In the overcurrent limiting circuit of the power FET made into an IC shown in FIG. 1, 10 is a multi-source structure (first
Source 10a, second source 10b)
It is an S-type power FET, the drain of which is the power supply terminal 20.
And the first source (current output terminal) 10a is connected to I
It is connected to the current output terminal (external load connection terminal) 11 of C. Reference numeral 12 is a load circuit connected to the current output terminal 11.

Reference numeral 13 is a power for controlling the gate potential of the power FET 10 by turning on / off the supply output of the charging current to the gate capacitance C of the power FET 10 from the built-in current source 13a according to the power FET drive control signal. It is a FET drive circuit.

Reference numeral 21 is connected to the second source (current detection terminal) 10b of the power FET, and the current detection terminal 1 is connected.
It is a resistance element that converts a current flowing through 0b into a voltage signal and outputs the voltage signal.

22b receives the output from the resistance element 21, compares the input voltage with a predetermined reference voltage, and when the input voltage becomes larger than the reference voltage (detection current flowing through the current detection terminal 10b). Is a linear type voltage comparison circuit that outputs a current according to the overcurrent.

Reference numeral 23 denotes an output NPN transistor to which the output current of the voltage comparison circuit 22b is given as a base current, and the power F between the collector and the emitter thereof.
It is connected between the output node of the ET drive circuit 13 and the ground node.

The voltage comparison circuit 22b and the output transistor 23 detect the overcurrent of the power FET, extract the output current of the power FET drive circuit 13 according to the overcurrent, and supply it to the ground potential. F
A voltage comparison type current control circuit 24b that controls the gate potential of the ET 10 is configured.

The resistance value of the resistance element 21 is comparatively small in order to reduce the influence of the potential fluctuation on the current detection terminal 10b of the power FET due to the voltage drop generated in the resistance element 21. It is set to be small.

Therefore, the voltage comparison circuit 22b needs to operate at a low voltage level in order to compare the voltage drop generated in the resistance element 21 with the reference voltage Vref and detect a minute potential difference between the two. , Bipolar transistors are used.

Also, the output NPN transistor 2
Since No. 3 is driven by the output of the voltage comparison circuit 22b which operates at a low voltage level, a bipolar transistor in which the variation in the base-emitter voltage is smaller than the variation in the threshold voltage of the MOS transistor is used.
Further, in the output NPN transistor 23, a large collector current flows when the output current of the power FET drive circuit 13 is drawn and supplied to the ground potential, so that a relatively large current also flows to its base.

Next, the structure and operation of the voltage comparison circuit 22b will be described. The voltage comparison circuit 22b is supplied with an input voltage Vin and a predetermined reference voltage Vref corresponding to respective bases, and the PNP type first transistors Q1 whose emitters are directly connected to each other to form a differential pair.
And the second transistor Q2, the emitter common connection node of the transistors Q1 and Q2 forming the differential pair, and the first transistor
Constant current source 25 connected to the power source potential (power source potential Vcc on the high potential side), the collector of the first transistor Q1 and the second power source potential (power source potential on the low potential side, ground potential Vss). ) Is connected between the collector and the emitter, and the collector and the base are connected to each other, and an NPN-type third transistor Q3 whose collector is the second transistor Q.
A second NPN-type transistor Q4 connected to the collector of the second transistor and having an emitter connected to the ground potential Vss, and connected between the collector of the fourth transistor Q4 and the base of the third transistor Q3. First resistance element R
1, the base of the fourth transistor Q4 and the third
And a second resistance element R2 connected between the base of the transistor Q3 and the base of the transistor Q3. The third transistor Q3
And the fourth transistor Q4 form a current mirror circuit.

In the operation of the voltage comparison circuit 22b, when the input voltage Vin is equal to the reference voltage Vref, the same current flows through the transistors Q1 and Q2 forming the differential pair, so that the output current from the voltage comparison circuit 22b is not generated. On the other hand, when the input voltage Vin is higher than the reference voltage Vref,
The currents of the transistors Q1 and Q2 forming the differential pair correspondingly decrease and increase. At this time, the currents of the transistors Q3 and Q4 of the current mirror circuit decrease, and most of the current flowing through the transistor Q2 (current corresponding to the overcurrent) is output as the base current of the output NPN transistor 23.

Next, the operation of the overcurrent limiting circuit having the above structure will be described. During normal operation, the impedance of the load circuit 12 is, for example, 12Ω, the voltage applied to the power supply terminal 20 is, for example, 12V, and the pulse signal input of the power FET drive circuit 13 is changed between 0V and 5V, for example, and the pulse signal output is obtained. Changes between 0V and, for example, 20V. At this time, when 20V is applied to the gate of the power FET 10, 1 is output from the current output terminal 10a of the power FET.
A flows, and a current of about 1/1000 (about 1 mA) flows to the current detection terminal 10b of the power FET 10.

In this state, the input voltage Vin is equal to the reference voltage V
Since a current equal to ref and equal to the transistors Q1 and Q2 forming the differential pair in the voltage comparison circuit 22b flows,
The output current from the voltage comparison circuit 22b does not occur.

At this time, since the current flows from the transistor Q1 to the bases of the transistors Q3 and Q4 of the current mirror circuit and the current flows from the transistor Q2 to the bases of the transistors Q3 and Q4 of the current mirror circuit, the offset of the input voltage is small.

At this time, since the resistance element R2 is connected to the base input side of the transistor Q4, the base current IB4 of the transistor Q4 is smaller than the base current IB3 of the transistor Q3, and the collector current of the transistor Q4. IC4 is the collector current I of transistor Q3
It is smaller than C3.

On the other hand, when the load impedance is lowered, for example, when the load is short-circuited, the output current of the power FET 10 and the detection current increase, and the detection current exceeds the reference current (overcurrent), the resistance element In the direction in which the input voltage Vin from 21 becomes slightly larger than the reference voltage Vref, the input voltage Vin
A minute potential difference occurs between the reference voltage Vref and the reference voltage Vref.

At this time, a transistor Q1 forming a differential pair,
The current in Q2 correspondingly decreases and increases, and the transistors Q3 and Q4 of the current mirror circuit decrease. Then, since a current flows from the transistor Q2 to the base of the transistor Q3 of the current mirror circuit via the resistance element R1, the collector current IC3 of the transistor Q3 of the current mirror circuit flows from the transistor Q2 to the transistor Q3 of the current mirror circuit.
However, since the resistance element R2 is connected to the base input side of the transistor Q4, the base current IB4 of the transistor Q4 is insufficient, and the collector current IC4 of the transistor Q4 hardly flows. As a result, most of the current flowing through the transistor Q2 (current corresponding to the overcurrent) is output as the base current of the output NPN transistor 23, and the output NPN transistor 23 extracts the output current of the power FET drive circuit 13. The power FET 10 is protected by feedback control so that the power FET 10 is turned off.

At this time, since the resistance element R1 is connected to the current mirror-connected transistors Q3 and Q4, the operating gain of the voltage comparison circuit 22b is relatively small.
It is possible to control the output current linearly.

At this time, since the operation gain of the voltage comparison circuit 22b included in the power transistor feedback control path is relatively low, the operation at the time of detecting the overcurrent of the power FET 10 and performing the feedback control is not unstable. It is possible to prevent oscillation of the overcurrent limiting circuit.

FIG. 2 shows that when the power supply voltage is applied to the power supply terminal 20 in the load short circuit state in the circuit of FIG. 1, the control operation of the power FET feedback control path is stably performed, and the drain / source of the power FET is It shows that the waveform of the inter-current IDS is stable.

FIG. 3 shows a modification of the voltage comparison type current control circuit shown in FIG. This voltage comparison type current control circuit is shown in FIG.
In order to further reduce the operation gain of the voltage comparison type current control circuit shown therein, the emitters of the transistors Q1 and Q2 forming a differential pair in the voltage comparison circuit 22b are respectively connected via the resistance element R. It is modified to connect to the common connection node.

When the operating gain of the voltage comparison type current control circuit is reduced in this way, the linear controllability of the output current as described above is improved, and the operation at the time of feedback control in the overcurrent limiting circuit using this is further improved. Stabilize.

The overcurrent limiting circuit of the present invention is not limited to the DMOS power FET of the above-mentioned embodiment, but is a voltage drive type power supply having a multi-cell structure including an IGBT (insulated gate bipolar transistor) having a multi-emitter structure. It is applicable to transistors.

[0054]

As described above, according to the voltage comparison type current control circuit of the present invention, the operating gain is relatively small, the output current can be linearly controlled, and the input voltage offset at the time of output reversal is reduced. It is small and can be applied to minute potential difference detection circuits. Further, according to the overcurrent limiting circuit of the present invention, it is possible to prevent the oscillation when the overcurrent of the protected semiconductor element is detected and the feedback control is performed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an overcurrent limiting circuit of a power FET according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing that the waveform of a drain-source current IDS of a power FET is stable when a power supply voltage is applied to a power supply terminal when a load is short-circuited in the circuit of FIG.

FIG. 3 is a circuit diagram showing a modification of the voltage comparison type current control circuit in FIG.

FIG. 4 is a circuit diagram showing a conventional power FET overcurrent limiting circuit.

5 is a waveform diagram showing that the waveform of a drain-source current IDS of a power FET is unstable when a power supply voltage is applied to a power supply terminal in a load short circuit state in the circuit of FIG.

FIG. 6 is a circuit diagram showing another conventional example of an overcurrent limiting circuit for a power MOSFET.

[Explanation of symbols]

10 ... DMOS type power FE having multi-source structure
T, 10a ... First source (current output terminal) of power FET, 10b ... Second source (current detection terminal) of power FET, 11 ... Current output terminal of IC, 12 ... Load circuit, 13 ... Power FET Drive circuit, 20 ... power supply terminal, 2
1 ... Resistance element for voltage conversion, 22b ... Voltage comparison circuit, 2
3 ... Output NPN transistor, 24b ... Voltage comparison type current control circuit.

Claims (4)

[Claims] 1. A first transistor and a second transistor which are supplied with an input voltage and a reference voltage corresponding to their respective bases, have the same bipolar type polarity, and are connected so as to form a differential pair. A constant current source connected between a first power supply potential and a common emitter connection node of the first transistor and the second transistor forming the differential pair, and a collector of the first transistor and a second A third bipolar transistor having a collector-emitter connected to the power supply potential of 1, and a collector-base connected to each other and having a polarity opposite to that of the first transistor; A bipolar type transistor having a polarity, the collector of which is connected to the collector of the second transistor and the emitter of which is connected to the second power supply potential; A fourth transistor; a first resistance element connected between the collector of the fourth transistor and the base of the third transistor; a base of the fourth transistor and a base of the third transistor A second resistance element connected between and, and a base having a same polarity as the fourth transistor, a base connected to a collector of the fourth transistor, and a current source connected to the collector, The emitter is the second
And a fifth transistor for bipolar current control connected to the power supply potential of 1. 2. The voltage comparison type current control circuit according to claim 1, wherein each of the first transistor and the second transistor forming the differential pair has an emitter common through the third resistance element. A voltage comparison type current control circuit characterized by being connected to a connection node. 3. A voltage-driven power transistor having a multi-cell structure, and a charge-current supply output to a control electrode capacitance of the power transistor is controlled to be turned on / off according to a drive control signal for the power transistor. The power transistor drive circuit for controlling the control electrode potential of the power transistor; the current-voltage conversion resistance element which causes a voltage drop according to the detection current flowing through the current detection terminal of the power transistor; 2 has the same configuration as the voltage comparison type current control circuit, the voltage generated in the current-voltage conversion resistance element is given as the input voltage, and the collector of the fifth transistor for current control is the power transistor. And a second power supply potential connected between the output node of the drive circuit and the second power supply potential. A voltage for controlling the control electrode potential of the power transistor by detecting an overcurrent of the detection current flowing through the current detection terminal of the power transistor and extracting the output current of the power transistor drive circuit according to the detected overcurrent. An overcurrent limiting circuit comprising a comparison type current control circuit. 4. The overcurrent limiting circuit according to claim 3, wherein the voltage drive type power transistor having the multi-cell structure is a double diffusion type insulated gate power field effect transistor having a multi-source structure. Characteristic overcurrent limiting circuit.