JP2003009376A - Power semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably operate an overcurrent protection circuit, whereby in power ICs, the influence of VBE of an overcurrent-sensing transistor due to its temperature dependence can be compensated and the period for a main element subjected to an overcurrent can be always sensed during its operation, with the sensing point thereof becoming nearly a fixed value. SOLUTION: By making the flow through a shunting element M2 and a detection resistor R1 a small monitoring current which is proportional to the main current flowing through an output-oriented main element M1, the fact that the detection resistor has a voltage-drop which exceeds a predetermined value is sensed by a bipolar- type overcurrent detecting transistor Q1 so as to detect the time of the main element which is subjected to an overcurrent. In this case, by connectively providing a temperature-characteristic compensating resistance-element R2 between the base of the overcurrent-detecting transistor and the other end of the shunting element than its shunting point, there is provided a temperature-characteristic compensating power- supply circuit for making a current flow with the temperature-characteristic compensating resistance element R2 generate its voltage drop, having the direction which cancels the change of the VEB of the overcurrent sensing transistor, which depends on the temperature thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power semiconductor device, and more particularly to an overcurrent detection circuit for detecting an overcurrent flowing in a shunt element for flowing a small current proportional to a main current flowing in an output main element. The present invention is applied to a large current output control integrated circuit (power IC) for driving a motor, for example.

[0002]

2. Description of the Related Art For example, a motor drive power IC has an insulated gate field effect transistor (MOSFET) as an output main element for switching a large load current (motor drive current), and An overcurrent detection circuit is often built in to detect the time and protect the IC from thermal damage. In this case, the overcurrent detection circuit is configured to detect the overcurrent time of the shunt element for flowing a small current proportional to the main current flowing through the main element.

FIG. 6 shows a MOSF as a main element and a shunt element.
The conventional example of the output circuit part of the power IC using ET is shown.

In the power IC shown in FIG. 6, a small monitor current proportional to the main current flowing in the main element M1 is made to flow in the shunt element M2, this monitor current is made to flow in the resistance element R1 for current detection, and this resistance element R1 Generate a voltage drop across both ends. In this case, it is preset so that the voltage drop of the resistance element R1 at the time of overcurrent of the shunt element M2 exceeds the threshold voltage of the bipolar transistor for overcurrent detection (for example, the base-emitter voltage VBE of the NPN transistor Q1). If so, the overcurrent detection transistor Q1 is triggered when the shunt element M2 is overcurrent, a control current flows from the predetermined power supply to the overcurrent detection transistor Q1, and a control signal corresponding to the control current is output. Then, the control signal detects the overcurrent of the main element M1 and operates an overcurrent protection circuit (not shown) to control the main element M1 so as to protect the main element M1 from damage due to the overcurrent.

The NPN transistor Q1 for detecting the overcurrent is
VBE has a negative temperature characteristic (-2 mV / ° C), and the resistance value of the resistance element R1 for current detection varies depending on the process. Therefore, the overcurrent detection circuit in FIG. When a temperature change such as a temperature rise occurs, the detection value of the overcurrent detection transistor Q1 greatly varies.

In this case, the detection by the overcurrent detection transistor Q1 is intended to limit the limit of the large current at the time of overcurrent of the main element M1, and the detection value of the overcurrent detection transistor Q1 is The minimum variation value defines the specifications.

However, when the variation range of the detection value of the overcurrent detection transistor Q1 is large, the IC may be worst case.
The thermal breakdown of the IC and the disconnection of the bonding wiring / aluminum wiring inside the IC occur, which cannot be ignored with the increase in the current of the IC output, so a redundant design considering it is required.

FIG. 7 shows how the relationship between the output current IOUT and the overcurrent detection output (overcurrent detection characteristic) in the overcurrent detection circuit in FIG. 6 varies depending on the IC temperature.

That is, when the IC temperature becomes higher than the middle temperature (for example, room temperature 25 ° C.), the VBE of the detection transistor Q1 becomes small, and the detection transistor Q1 against the overcurrent of the main element M1 is detected.
Detection value is lower than the detection value at medium temperature. That is, the point of the main current corresponding to the voltage drop across the detection resistor R1 at which the detection transistor Q1 turns on becomes lower than the point at the middle temperature.

Contrary to the above, when the IC temperature becomes lower than the middle temperature, VBE of the detection transistor Q1 becomes large and the main element
The detection value of the detection transistor Q1 at the overcurrent of M1 becomes higher than the detection value at the middle temperature. That is, the detection transistor Q1
The point of the main current corresponding to the voltage drop across the detection resistor R1 that turns on becomes higher than the point at the middle temperature.

As described above, if the overcurrent detection characteristic of the overcurrent detection circuit varies depending on the IC temperature, the overcurrent protection circuit cannot operate stably.

8 and 9 in Japanese Patent Laid-Open No. 8-111524 disclose an overcurrent detection circuit using an IGBT as a main element and a shunt element, and these circuits are also described above. There is such a problem.

[0013]

As described above, in the conventional overcurrent detection circuit, the current flowing in the shunt element for flowing a small monitor current proportional to the main current flowing in the output main element causes both ends of the detection resistor. There is a temperature dependency of the VBE of the transistor that detects the overcurrent of the main element based on the voltage drop that occurs in the main element, and the detected value of the overcurrent of the main element has temperature dependency, so the overcurrent protection circuit operates stably. There was a problem that I could not.

The present invention has been made to solve the above problems, and can compensate the influence of the temperature dependence of VBE of the overcurrent detection transistor, and the overcurrent of the main element during operation can always be kept at a substantially constant value. It is an object of the present invention to provide a power semiconductor device having an overcurrent detection circuit that can be detected at the detection point and can operate the overcurrent protection circuit in a stable manner.

[0015]

A first power semiconductor device according to the present invention comprises an output main element consisting of a first transistor having one end connected to an output terminal and the other end connected to a ground terminal. A shunt element for flowing a small monitor current proportional to a main current flowing through the main element, the shunt element including a second transistor having one end connected to the main element and gates connected to each other; A bipolar type overcurrent detector connected between the other end and the ground terminal for detecting a current through which the monitor current flows and a bipolar type overcurrent detecting resistor for detecting that the voltage drop of the resistive element for current detection reaches a predetermined value. A current detection transistor, a resistance element for temperature characteristic compensation connected between the base of the overcurrent detection transistor and the other end of the shunt element, and a resistance element for temperature characteristic compensation, and Presence was the characterized by comprising a current source circuit for temperature compensation to flow a current for generating the direction of the voltage drop canceling the variation of the base-emitter voltage VBE of the overcurrent detection transistor.

A second power semiconductor device of the present invention comprises a first main element for output, which comprises a first transistor having one end connected to an output terminal and the other end connected to a ground terminal, and the first main element for output. 1 main element and a second transistor whose one end is connected to each other and whose gates are connected to each other.
First shunt element for flowing a small monitor current proportional to the main current flowing through the main element of the first element, and a first current detecting element connected between the other end of the first shunt element and the ground terminal. Resistance element, a bipolar type first overcurrent detection transistor for detecting that the voltage drop of the first current detection resistance element has reached a predetermined value, and the first overcurrent detection transistor A first temperature characteristic compensating resistance element connected between the base of the first temperature dividing element and the other end of the first shunt element, and the first temperature characteristic compensating resistance element including the first temperature characteristic compensating resistance element. 1 base of overcurrent detection transistor
A first current source circuit for compensating temperature characteristics, which flows a current for causing a voltage drop in a direction of canceling a change in the emitter-to-emitter voltage VBE1, and one end of which is connected to the output terminal and the other end of which is connected to a power supply terminal. A second main element for output comprising a second transistor, and a second transistor having one end connected to the second main element and gates connected to each other, the second main element A second shunt element for flowing a small monitor current proportional to the main current flowing through
The voltage drop between the second current detection resistance element connected between the other end of the second current shunt element and the power supply terminal and the second current detection resistance element has reached a predetermined value. And a second temperature characteristic connected between the base of the second overcurrent detecting transistor and the other end of the second shunt element. A voltage drop is generated in the compensating resistance element and the second temperature characteristic compensating resistance element in the direction of canceling the temperature-dependent change in the base-emitter voltage VBE2 of the second overcurrent detection transistor. A second current source circuit for compensating a temperature characteristic for flowing a current for causing the current to flow, and a logical sum of the detection output of the first overcurrent detection transistor and the detection output of the second overcurrent detection transistor. To output the control signal Is characterized by.

In a third power semiconductor device of the present invention, one end for output consisting of a first transistor having one end connected to an output terminal and the other end connected to a ground terminal, and the first main element for output. 1 main element and a second transistor whose one end is connected to each other and whose gates are connected to each other.
First shunt element for flowing a small monitor current proportional to the main current flowing through the main element of the first element, and a first current detecting element connected between the other end of the first shunt element and the ground terminal. Resistance element, a bipolar type first overcurrent detection transistor for detecting that the voltage drop of the first current detection resistance element has reached a predetermined value, and the first overcurrent detection transistor A first temperature characteristic compensating resistance element connected between the base of the first temperature dividing element and the other end of the first shunt element, and the first temperature characteristic compensating resistance element including the first temperature characteristic compensating resistance element. 1 base of overcurrent detection transistor
A first current source circuit for compensating temperature characteristics, which flows a current for causing a voltage drop in a direction of canceling a change in the emitter-to-emitter voltage VBE1, and one end of which is connected to the output terminal and the other end of which is connected to a power supply terminal. A second main element for output composed of a second transistor, and a second transistor having the other end connected to the second main element and the gates connected to each other. A second shunt element for passing a small monitor current proportional to the main current flowing through the element,
The voltage drop between the second current detecting resistance element connected between one end of the second shunt element and the output terminal and the second current detecting resistance element has reached a predetermined value. Second overcurrent detecting transistor for detecting the temperature, and a second temperature characteristic compensating device connected between the base of the second overcurrent detecting transistor and one end of the second shunt element. To cause a voltage drop in the direction of canceling the temperature-dependent change in the base-emitter voltage VBE2 of the second overcurrent detection transistor in the second resistance element and the second temperature characteristic compensation resistance element. And a second current source circuit for compensating the temperature characteristic for flowing the current of the above-mentioned current, and taking the logical sum of the detection output of the first overcurrent detection transistor and the detection output of the second overcurrent detection transistor. To output a control signal Is characterized by.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment> FIG. 1 shows a first embodiment of the present invention.
3 shows an output circuit unit of the power IC according to the embodiment.

The output circuit section shown in FIG. 1 has a main element M1 for "L" side driving for switching the operation in which a large current is supplied from an external load connected to the output terminal OUT. Then, it has a shunt element M2 for flowing a small monitor current proportional to the main current flowing in the main element M1, and an overcurrent detection circuit for detecting an overcurrent time of this shunt element M2, using an overcurrent detection output. It controls the output current of the power IC so as to protect it from thermal damage.

The output transistor constituting the main element M1 is an enhancement type MOSFET, and the shunt transistor constituting the shunt element M2 is an enhancement type MOSFET.

Each of the transistors M1 and M2 is connected to the driving gate terminal of the power IC through the gate input resistance after the gates thereof are commonly connected, and the drains of the transistors M1 and M2 are connected to the output terminal OUT of the power IC. Is commonly connected to the source of the output transistor M1
It is connected to the GND terminal, and the source of the shunt transistor M2 is connected to the GND terminal via the resistance element R1 for current detection. The output terminal OUT of the power IC is connected to the external DC power supply via the external load.

Q1 is an overcurrent detecting bipolar transistor (NPN transistor in this example) for detecting a voltage drop occurring across the resistor element R1. The emitter of this detection transistor Q1 is connected to the GND terminal, and the resistance element RL that acts as a collector load (control signal generation) between the collector and the power supply voltage (VCC) node of the control circuit system.
Are connected.

Further, a resistance element R2 for temperature characteristic compensation is connected between the base of the detection transistor Q1 and the source of the shunting transistor M2, and the resistance element R2 for temperature characteristic compensation is connected to the temperature. Dependent detection transistor
A current source circuit is provided for compensating the temperature characteristics that causes a current to flow that causes a voltage drop in the direction that cancels the change in VBE of Q1.

This temperature characteristic compensating current source circuit includes a Vt proportional current source 11 for supplying a current proportional to the thermal voltage Vt having a positive temperature characteristic based on, for example, VCC of the control circuit system,
The current mirror circuit 12 is configured to flow a current equal to the current of the Vt proportional current source 11 to the resistance element R2 for temperature characteristic compensation.

The current mirror circuit 12 includes an input side NPN transistor Q2 through which an output current of the Vt proportional current source 11 flows.
And an output side NPN transistor Q3 through which a current equal to the current of the input side transistor Q2 flows.The output node of this output side transistor Q3 is connected to one end side of the resistance element R2 for temperature characteristic compensation and the transistor Q1 for detection. It is connected to the base. In this case, the NP of the current mirror circuit 12
The N transistors Q2 and Q3 have the same polarity as the detecting transistor Q1.

FIG. 2 is a circuit diagram showing, as an example of the Vt proportional current source 11 in FIG. 1, a configuration similar to that of a current source in a bandgap voltage source, for example.

This Vt proportional current source is composed of a resistor element R3, a collector and a base of which are connected to each other between the VCC node and the GND.
The collector and emitter of N-transistor Q5 are connected in series. Also, between the VCC node and the ground node,
A resistance element R4, a base-collector-connected PNP transistor Q6, an emitter and a collector, two NPN transistors Q7 and Q8, a collector and an emitter, and a resistance element R5 are connected in series.

In this case, the bases of the NPN transistor Q4 and the NPN transistor Q7, whose collectors and bases are connected to each other, are connected to each other. Also, NPN transistor Q5
And Q8 have an emitter current ratio (area ratio) set to 1: N (a positive integer). These two NPN transistors Q5
And Q8 have their collectors and bases connected (cross-connected) to each other.

Further, the resistor element R6, the emitter and collector of the PNP transistor Q9, and the input side transistor Q2 of the current mirror circuit 12 in FIG. 1 are connected in series between the VCC node and GND. In this case, the PNP transistor Q9 and the PNP in which the base and collector are connected to each other
The bases of the transistor Q6 are connected to each other.

The operation of the Vt proportional current source having the above-described structure is well known, and therefore its explanation is omitted.
It is possible to supply a current proportional to Vt from the transistor Q9 to the transistor Q2 on the input side of the current mirror circuit 12 in FIG.

In the output circuit section shown in FIG. 1, when a predetermined positive gate voltage is applied from the main element drive circuit between the drive gate terminal and the GND terminal, the external DC power supply passes through the external load. Drain current flows through the output transistor M1. In addition, a small drain current (monitor current) proportional to the drain current of the output transistor M1 flows through the shunt transistor M2.

This monitor current flows through the resistance element R1 for detection, and a voltage drop occurs across the resistance element R1. In this case, it is preset so that the voltage drop of the resistance element R1 at the time of overcurrent of the shunt transistor M2 exceeds a certain threshold voltage determined by the VBE of the detection transistor Q1. Then, the detection transistor Q1 is triggered when the overcurrent of the shunt transistor M2 (in other words, during the overcurrent of the output transistor M1) causes the resistance element RL for generating the control signal and the detection transistor Q1 from the VCC power supply. A control current flows, and a control signal is generated across the resistance element RL for generating a control signal according to the control current. Then, using this control signal, the output current is reduced (for example, the output transistor M1 is turned off), and control is performed so as to prevent the power IC from being destroyed due to an overcurrent.

FIG. 3 shows how the relationship between the output current IOUT and the overcurrent detection output (overcurrent detection characteristic) in the overcurrent detection circuit in FIG. 1 varies depending on the IC temperature.

VBE of the detection transistor Q1 has a negative temperature characteristic (-2 mV / ° C.), and VB of the detection transistor Q1 depends on temperature change such as temperature rise during the operation of the power IC.
E changes.

At this time, in the present embodiment, a current proportional to the thermal voltage Vt from the Vt proportional current source 11 is applied to the resistance element R2 for temperature characteristic compensation connected to the base of the detection transistor Q1. It is supplied via 12 and causes a voltage drop in a direction to cancel the change in VBE of the detection transistor Q1 depending on the temperature. As a result, the temperature dependence of the detection value of the detection transistor Q1 can be almost ignored, and the overcurrent of the main current can be detected at a substantially constant point.

That is, when the temperature of the IC becomes higher than the middle temperature (for example, room temperature of 25 ° C.) as the temperature rises during the circuit operation, the VBE of the detection transistor Q1 becomes smaller. In this case, since the current proportional to the thermal voltage Vt from the Vt proportional current source 11 becomes large, the voltage drop that occurs in the resistance element R1 for temperature characteristic compensation becomes large, and the base voltage of the detection transistor Q1 is reduced by the reduction amount of VBE. Since it is lowered as much as, it acts to cancel the temperature dependence of VBE.

Contrary to the above, when the IC temperature becomes lower than the middle temperature, the voltage between the base and emitter of the transistor Q1 for detection is detected.
VBE increases. In this case, since the current proportional to the thermal voltage Vt from the Vt proportional current source 11 becomes small, the voltage drop generated in the resistance element R1 for temperature characteristic compensation becomes small, and the base voltage of the detection transistor Q1 is increased by the increment of VBE. Since it is raised as much as, it acts to cancel the temperature dependence of VBE.

Therefore, the detection value of the detection transistor Q1 at the time of overcurrent of the main element M1 is less deviated from the detection value at the middle temperature even if the IC temperature fluctuates, and the detection transistor Q1 is turned on. The overcurrent detection point of the main current corresponding to the voltage drop across the detection resistor R1 is maintained substantially constant.

Further, even if the resistance value of the resistance element R1 for current detection varies depending on the process, by setting the resistance element R2 for temperature characteristic compensation to an appropriate resistance value, the temperature range is almost at the center of the change range of the IC temperature. The overcurrent detection point of the main current is set to the desired optimum value.

At this time, the resistance element R1 for current detection and the resistance element R2 for temperature characteristic compensation are made of the same material (for example, polysilicon) so that the resistance value at the approximate center of the change range of the IC temperature is an optimum value. It becomes easy to set to.

A resistance element may be inserted between the emitter of the detection transistor Q1 and the GND terminal in order to reduce the influence of variations in VBE of the detection transistor Q1.

Further, in this example, the main element M1 and the shunt element
Although MOSFETs are used for M2, respectively, the same can be applied to the case of using an insulated gate bipolar transistor (IGBT).

<Second Embodiment> FIG. 4 shows a second embodiment of the present invention.
3 shows an output circuit unit of the power IC according to the embodiment.

Compared with the output circuit section described above with reference to FIG. 1, this output circuit section has an "H" side main circuit for switching the operation of supplying a large current to the external load connected to the output terminal OUT. Element M1H and this "H" side main element M1
"H" side shunt element M2H, which sends a small monitor current proportional to the main current flowing in H, and this "H" side shunt element
The difference is that the "H" side overcurrent detection circuit that detects the overcurrent of M2H is added. Others ("L" side main element M
1, the "L" side shunt element M2 and the "L" side overcurrent detection circuit) are the same, so the same reference numerals as in FIG.

As the "H" side main element M1H, an output transistor composed of an enhancement type MOSFET is connected between the "H" side power supply (VCCH) node and the output terminal OUT. As an "H" side shunt element M2H, an enhancement type MOSF between the VCCH node and the output terminal OUT.
A shunt transistor consisting of ET is connected.

In the "H" side overcurrent detection circuit, a resistance element Rs for current detection connected between the VCCH node and the drain of the "H" side shunt element M2H, and the voltage drop of this resistance element Rs are predetermined. PNP transistor Q11 for overcurrent detection to detect that the value has been reached, and this PNP transistor Q11
Of the collector load resistance element R11, the signal generated by this resistance element R11 is input to the base, and the emitter is connected to the GND terminal for the signal inversion NPN transistor Q12 and the "H" side shunt transistor M2H. A resistor element Rt for temperature characteristic compensation connected between the drain and the base of PNP transistor Q11 for overcurrent detection, and this resistor element Rt.
And a current source circuit for temperature characteristic compensation in which an output node is connected to a connection node between the base of the NPN transistor for overcurrent detection.

The collector of the NPN transistor Q12 for signal inversion of the "H" side overcurrent detection circuit and the collector of the NPN transistor Q1 for overcurrent detection of the "L" side overcurrent detection circuit are commonly connected (wired). Or connection).

The current source circuit for temperature characteristic compensation of the "H" side overcurrent detection circuit has a resistance element Rt for temperature characteristic compensation and a VB of the PNP transistor Q11 for temperature-dependent overcurrent detection.
In order to cause a voltage drop in the direction that cancels the change in E, a current equal to the current of the Vt proportional current source 11 used in the "L" side overcurrent detection circuit is set to a resistance element Rt for temperature characteristic compensation.
It is what is flushed to.

As an example of this configuration, a current equal to the current of the NPN transistor Q2 on the input side of the current mirror circuit 12 of the "L" side overcurrent detection circuit is passed through the NPN transistor Q10, and the current of this NPN transistor Q10 is passed through the PNP transistor Q10. The PNP current mirror circuit 13 composed of Q13 and Q14 is configured to be folded back and flow to the resistance element Rt for temperature characteristic compensation. In this case, PN of PNP current mirror circuit 13
The P transistors Q13 and Q14 have the same polarity as that of the "H" side overcurrent detection PNP transistor Q11.

<Modification of Second Embodiment> FIG. 5 shows an output circuit section of a power IC according to a modification of the second embodiment of the present invention.

This power IC differs from the output circuit section shown in FIG. 4 in the configuration of the "H" side overcurrent detection circuit.
Others ("L" side main element M1, "L" side shunt element M
2, "L" side overcurrent detection circuit, "H" side main element M1H
, "H" side shunt element M2H) are the same, so the same parts as those in FIG.

The "H" side overcurrent detection circuit includes a resistance element R1H for current detection connected between the source of the "H" side diversion transistor M1H and the output terminal OUT, and a voltage drop of this resistance element R1H. And a PNP current mirror circuit 51 that has an overcurrent detection transistor Q1H for detecting that it has reached a predetermined value, and an input-side PNP transistor Q51 connected between the collector of this transistor Q1H and the VCCH node. , PN on the output side of this PNP current mirror circuit 51
The load resistance element R51 connected between the collector of the P-transistor Q52 and the GND terminal and the signal generated by this load resistance element R51 are input to the base, the emitter is connected to the GND terminal, and the collector is connected to the VCC node. Connected signal inversion NPN transistor Q53, source of "H" side shunt transistor M1H and PNP transistor for overcurrent detection
Resistance element R2H connected between Q1H and temperature characteristic compensation
And this resistor element R2H and transistor Q1 for overcurrent detection.
And a current source circuit for temperature characteristic compensation, in which an output node is connected to a connection node with the base of H.

Then, the collector of the NPN transistor Q53 for signal inversion of the "H" side overcurrent detection circuit and the collector of the NPN transistor Q1 for overcurrent detection of the "L" side overcurrent detection circuit are commonly connected (wired). Or connection).

The current source circuit for compensating the temperature characteristic of the "H" side overcurrent detection circuit is composed of the resistance element R2H for compensating the temperature characteristic.
PNP transistor Q1H for temperature-dependent overcurrent detection
In order to cause a voltage drop in the direction that cancels the change in VBE, a current equal to the current of Vt proportional current source 11 used in the "L" side overcurrent detection circuit is set to the resistance element R2 for temperature characteristic compensation.
It is the one that flows to H.

As an example of this configuration, the current of the current mirror circuit of the "L" side overcurrent detection circuit is folded back by the NPN transistor Q10 and the PNP transistors Q54 and Q5.
5 PNP current mirror circuit 52
The current of the current mirror circuit 52 is configured to be returned by the NPN current mirror circuit 53 composed of NPN transistors Q56 and Q57 and flow to the resistance element R2H for temperature characteristic compensation. In this case, the NPN transistors Q56 and Q57 of the NPN current mirror circuit 53 have the same polarity as the NPN transistor Q1H for "H" side overcurrent detection.

The overcurrent detection operation of the "H" side overcurrent detection circuit having the above configuration is performed in accordance with the overcurrent detection operation of the "H" side overcurrent detection circuit of the second embodiment. And then
The logical sum of the overcurrent detection signal of the H "side overcurrent detection circuit and the overcurrent detection signal of the" L "side overcurrent detection circuit is calculated and becomes the control signal output.

[0058]

As described above, according to the overcurrent detection circuit of the power semiconductor device of the present invention, the influence of the temperature dependence of VBE of the overcurrent detection transistor can be compensated, and the overcurrent of the main element during operation can be compensated. The time can always be detected at a detection point having a substantially constant value, and the overcurrent protection circuit can operate stably.

Therefore, especially for the case where a large number of switching elements are connected in parallel to form a power switching element for increasing the capacity, or for a power integrated circuit in which a main element and a shunt element are monolithically formed on the same substrate. The present invention can be effectively used.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an output circuit section of a power IC according to a first embodiment.

FIG. 2 is a circuit diagram showing an example of a Vt proportional current source in FIG.

3 is a characteristic diagram showing how the overcurrent detection characteristic of the overcurrent detection circuit in FIG. 1 varies depending on the IC temperature.

FIG. 4 is a circuit diagram showing an output circuit section of a power IC according to a second embodiment.

5 is a circuit diagram showing a modified example of the overcurrent detection circuit in FIG.

FIG. 6 is a circuit diagram showing a conventional example of an output circuit section of a power IC using MOSFETs as a main element and a shunt element.

7 is a characteristic diagram showing how the overcurrent detection characteristic of the overcurrent detection circuit in FIG. 6 varies depending on the IC temperature.

[Explanation of symbols]

M1 ... Main element (transistor for output), M2 ... shunt element (shunt transistor), OUT… Output terminal, GND ... ground terminal, R1 ... Resistance element for current detection, Q1 ... Transistor for overcurrent detection, RL: resistance element for collector load (control signal generation), R2 ... Resistance element for temperature characteristic compensation, 11 ... Vt proportional current source for temperature characteristic compensation, 12 ... Current mirror circuit.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 27/06 H01L 23/56 C H02H 3/087 H02M 1/00 (72) Inventor Hiroshi Yoshino Kawasaki, Kanagawa Prefecture 25, 1 Honcho, Ekimae, Kawasaki-ku, Ichi F-term in Toshiba Microelectronics Corporation (reference) 5F038 BH06 BH16 EZ20 5F082 AA04 BC03 BC09 BC15 FA03 FA16 FA20 5G004 AA04 AB02 BA03 BA04 DA02 DA04 DC12 EA01 5H740 AA08 BA12 BA15 BB01 BB04 MM01 KK04

Claims (6)

[Claims] 1. An output main element comprising a first transistor having one end connected to an output terminal and the other end connected to a ground terminal; and an output main element having one end connected to the main element and gates connected to each other. A second shunt transistor, which is configured to pass a small monitor current proportional to a main current flowing through the main element, and is connected between the other end of the shunt element and the ground terminal.
A resistance element for current detection through which the monitor current flows, a bipolar type overcurrent detection transistor for detecting that the voltage drop of the resistance element for current detection has reached a predetermined value, and the overcurrent detection transistor A temperature-compensation resistance element connected between the base and the other end of the shunt element, and a base-emitter voltage of the temperature-dependent overcurrent detection transistor in the temperature-compensation resistance element. VB
A power semiconductor device, comprising: a current source circuit for temperature characteristic compensation, in which a current for causing a voltage drop in a direction of canceling a change in E is caused to flow. 2. The current source circuit for compensating for temperature characteristics comprises a Vt proportional current source for flowing a current proportional to a thermal voltage Vt, a bipolar type input side transistor for flowing a current of the Vt proportional current source, and a current equal to the transistor. 2. A current mirror circuit comprising a bipolar output-side transistor in which a current flows, and an output node of the output-side transistor is connected to one end of the resistance element for temperature characteristic compensation. Power semiconductor device. 3. The power semiconductor device according to claim 2, wherein each transistor of the current mirror circuit has the same polarity as that of the overcurrent detection transistor. 4. The power semiconductor device according to claim 1, wherein the resistance element for temperature characteristic compensation and the resistance element for current detection are made of the same material. . 5. A first main element for output composed of a first transistor having one end connected to an output terminal and the other end connected to a ground terminal, and one end connected to the first main element. A second shunt element having a second transistor whose gates are connected to each other, for passing a small monitor current proportional to the main current flowing through the first main element, and a second shunt element other than the first shunt element. A first current detecting resistance element connected between an end and the ground terminal; and a bipolar-type first resistance element for detecting that the voltage drop of the first current detecting resistance element has reached a predetermined value. A first overcurrent detection transistor; a first temperature characteristic compensation resistance element connected between the base of the first overcurrent detection transistor and the other end of the first shunt element; In the first resistance element for temperature characteristic compensation, A first current source circuit for temperature characteristic compensation, which flows a current for causing a voltage drop in a direction of canceling a change in the base-emitter voltage VBE1 of the dependent first overcurrent detection transistor, and the output terminal A second main element for output composed of a second transistor having one end connected to the power supply terminal and the other end connected to the power supply terminal, one end of the second main element and one end of the second main element connected to each other. A second shunt element for flowing a small monitor current proportional to a main current flowing through the second main element, the other end of the second shunt element and the power supply terminal. A second current detecting resistance element connected in between, and a bipolar type second overcurrent detecting transistor for detecting that the voltage drop of the second current detecting resistance element has reached a predetermined value. And the above A second resistance element for temperature characteristic compensation connected between the base of the overcurrent detection transistor and the other end of the second shunt element, and a second resistance element for temperature characteristic compensation, A second current source circuit for compensating temperature characteristics, in which a current for causing a voltage drop in a direction of canceling a change in the base-emitter voltage VBE2 of the second overcurrent detection transistor depending on temperature is flowed. Then, the control signal is output by taking the logical sum of the detection output of the first overcurrent detection transistor and the detection output of the second overcurrent detection transistor. 6. A first main element for output, which is composed of a first transistor whose one end is connected to an output terminal and whose other end is connected to a ground terminal, and one end of which is connected to the first main element. A second shunt element having a second transistor whose gates are connected to each other, for passing a small monitor current proportional to the main current flowing through the first main element, and a second shunt element other than the first shunt element. A first current detecting resistance element connected between an end and the ground terminal; and a bipolar-type first resistance element for detecting that the voltage drop of the first current detecting resistance element has reached a predetermined value. A first overcurrent detection transistor; a first temperature characteristic compensation resistance element connected between the base of the first overcurrent detection transistor and the other end of the first shunt element; In the first resistance element for temperature characteristic compensation, A first current source circuit for temperature characteristic compensation, which flows a current for causing a voltage drop in a direction of canceling a change in the base-emitter voltage VBE1 of the dependent first overcurrent detection transistor, and the output terminal A second main element for output composed of a second transistor having one end connected to the power supply terminal and the other end connected to a power supply terminal, the second main element and the other end connected to each other, and the gates connected to each other A second shunt element for flowing a small monitor current proportional to the main current flowing through the second main element, and one end of the second shunt element and the output terminal. A second current detecting resistance element connected in between, and a bipolar type second overcurrent detecting transistor for detecting that the voltage drop of the second current detecting resistance element has reached a predetermined value. And the above A second resistance element for temperature characteristic compensation connected between the base of the overcurrent detection transistor and one end of the second shunt element; And a second current source circuit for compensating temperature characteristics, which causes a current to generate a voltage drop in a direction of canceling a change in the base-emitter voltage VBE2 of the second overcurrent detection transistor depending on A power semiconductor device, wherein a control signal is output by ORing a detection output of the first overcurrent detection transistor and a detection output of the second overcurrent detection transistor.