JP2003078362A - Power semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To install an overcurrent restraining circuit which can prevent that an output transistor deviates from an allowable loss range and is thermally broken down, by detecting whether the output transistor operates in a safe operation region in a power IC. SOLUTION: This power semiconductor device is provided with the output transistor 2, a resistance element 17 for detecting an output current Ioc of the transistor 2, a circuit 40a for detecting a voltage between a collector and an emitter of the transistor 2, and the overcurrent restraining circuit 30a for controlling an overcurrent limiting value of an output current, according to a detection value of the circuit 40a. In the transistor 2, a driving voltage VIN is applied to a driving voltage terminal IN, and an output voltage Vo is led out from an output terminal OUT. The emitter and collector of the transistor 2 are connected with a part between the terminal IN and the terminal OUT, and a base of the transistor 2 is subjected to driving control by a driving circuit 1.

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 output element protection circuit for detecting an overcurrent of an output current flowing through an output element and protecting the output element from thermal damage due to the overcurrent. It is about.

[0002]

2. Description of the Related Art In a large current output control integrated circuit (power IC), a bipolar transistor, an insulated gate field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT) is used as an output element for switching a large load current. In many cases, an output element protection circuit is built in to detect the overcurrent of the output current and protect the output element from damage due to the overcurrent.
In this case, the output element protection circuit is configured to allow the output current flowing through the output element to also flow through the detection resistance element to be converted into a voltage value, and detect the overcurrent time based on the voltage value.

FIG. 5 shows a conventional example of an output circuit section of a power IC using PNP transistors as output elements.

In the output circuit section of the power IC shown in FIG. 5, the detection resistance element 17 and the output PNP transistor are provided between the drive voltage terminal IN to which the drive voltage VIN is applied and the output terminal OUT from which the output voltage Vo is taken out. The emitter and collector of 2 are connected, and the output current Ioc flowing through the output PNP transistor 2 also flows through the detection resistance element 17.

The output PNP transistor 2 is a drive circuit.
The PNP transistor for control is driven between the control terminal that is driven by 1 and controls the operation of this drive circuit 1 and the ground potential GND.
The 7 emitter and collector are connected.

The overcurrent suppressing circuit 30 includes a detection resistance element 17 and a control PNP transistor 7, converts the output current Ioc into a voltage value by the detection resistance element 17, and converts the current corresponding to the converted voltage into a reference current. It is detected whether the output current Ioc has reached the overcurrent limit value Ioc (max) by comparing with the above, and if the detection result is in the overcurrent state, the control PNP transistor 7 is turned on. PN for output by drive circuit 1
It controls the P-transistor 2 to the off state.

FIG. 6 shows the magnitude of the output current Ioc and VCE = of the output PNP transistor 2 in the output circuit section shown in FIG.
FIG. 6 is a characteristic diagram showing a relationship of the magnitude of (VIN-Vo).

In the output circuit section shown in FIG. 5, the current control is performed by detecting whether or not the output current Ioc has reached the preset fixed overcurrent limit value Ioc (MAX) as described above. However, the control is not always performed in a range smaller than the maximum allowable loss value of the output transistor 2.

For example, when the voltage of the drive voltage terminal IN rises too much or the output voltage Vo falls too much, the loss depending on the product of the emitter-collector voltage VCE of the output transistor 2 and the output current Ioc. Does not exceed the permissible loss of the output transistor 2, that is, whether or not the output transistor 2 operates in the safe operation area SOA. Therefore, the output transistor 2 may deviate from the permissible loss range and may be thermally destroyed, and the stable output voltage Vo may not be supplied to the load.

Specifically, for example, VIN = 10V, VCE = 5V, Io
In the steady operation of c = 1A, the loss of output transistor 2 is
Although it is 5W, for example, when VIN = 30V, VCE = 25V, and Ioc = 1A, the loss of the output transistor 2 becomes 25W.

[0011]

As described above, the conventional overcurrent suppressing circuit detects whether or not the output current Ioc flowing through the output element has reached the preset fixed overcurrent limit value Ioc (MAX). Current control is performed, but the current is not always controlled in a range smaller than the maximum allowable loss value of the output transistor, and the output transistor may deviate from the allowable loss range and be thermally destroyed. There was a problem.

The present invention has been made to solve the above problems, and detects whether or not the output transistor is operating in its safe operation area, and the output transistor deviates from the allowable loss range to generate heat. It is an object of the present invention to provide a power semiconductor device having an overcurrent suppressing circuit that can prevent damage.

[0013]

In a first power semiconductor device of the present invention, two electrodes are connected between a drive voltage terminal to which a drive voltage is applied and an output terminal from which an output voltage is taken out, and a control electrode. An output transistor whose drive is controlled by a drive circuit; an output current detection circuit for detecting an output current of the output transistor; a two-electrode voltage detection circuit for detecting a two-electrode voltage of the output transistor; And an overcurrent suppressing circuit for controlling an overcurrent limit value of the output current according to a value detected by the two-electrode voltage detecting circuit.

In the second power semiconductor device of the present invention, two electrodes are connected between the drive voltage terminal to which the drive voltage is applied and the output terminal from which the output voltage is taken out, and the control electrode is drive-controlled by the drive circuit. An output transistor, which is inserted and connected between the drive voltage terminal and one end of the output transistor, and includes a detection resistance element through which the same output current as the output transistor flows, and the detection resistance element, The output current is converted into a voltage value by a resistance element for detection, whether or not the output current has reached an overcurrent limit value is detected based on the converted voltage, and in the case of an overcurrent state, the drive circuit And an overcurrent suppressing circuit that controls the output transistor to be in an off state, and a voltage between two electrodes of the output transistor is detected. And a two-electrode voltage detection circuit that controls to change the overcurrent limit value by the overcurrent suppressing circuit according to the detected value so as not to exceed the allowable loss range when the range is outside the allowable loss range. It is characterized by having.

A third power semiconductor device of the present invention comprises an output transistor having two electrodes connected between a drive voltage terminal to which a drive voltage is applied and an output terminal from which the output voltage is taken out, and the output transistor. A drive circuit for driving and controlling a control electrode of the transistor; a control transistor connected between a control terminal for controlling the operation of the drive circuit and a ground potential; and a drive voltage terminal and one end of the output transistor. A detection resistance element inserted between the detection resistance element, a resistance element for current branching connected to one end of the detection resistance element on the output transistor side, and a voltage between two electrodes of the output transistor are detected and detected. By branching the current according to the value from the current flowing through the current branching resistance element, the remaining current of the current flowing through the current branching resistance element is used for the output. A resistance element for current branching, including a two-electrode voltage detection circuit for controlling the voltage between two electrodes of the transistor to control the allowable loss, a resistance element for detection, a control transistor, and a resistance element for current branching. Of the current flowing in the output current is compared with a reference current to detect whether or not the output current is an overcurrent state in which the allowable loss of the voltage between the two electrodes of the output transistor is taken into consideration. And an overcurrent suppressing circuit that controls the control transistor to control the output transistor to be in an off state by the drive circuit when in the overcurrent state.

[0016]

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.

In the output circuit section shown in FIG. 1, the driving voltage
The resistor element 17 for detection and the emitter-collector of the output PNP transistor 2 are connected between the drive voltage terminal IN to which VIN is applied and the output terminal OUT from which the output voltage Vo is taken out. The output current Ioc flowing through 2 also flows through the detection resistance element 17. The detection resistance element 17 is made of, for example, aluminum wiring and has a resistance value of, for example, 1Ω.

The output transistor 2 is driven by the drive circuit 1, and the control PNP transistor 7 is provided between the control terminal for controlling the operation of the drive circuit 1 and the ground potential GND.
The emitter and collector of are connected.

The overcurrent suppressing circuit 30 includes the detecting resistance element.
17 and control PNP transistor 7
Is converted into a voltage value by the detection resistance element 17, and whether or not the output current Ioc has reached the overcurrent limit value is detected based on this converted voltage.If the output current Ioc reaches the overcurrent limit value, the control transistor 7 And a function of controlling the output transistor 2 to be in an off state by the driver circuit 1.

The VCE voltage detection control circuit 40 detects the emitter-collector voltage VCE of the output transistor 2 so as not to exceed the allowable loss when the output transistor 2 is out of the allowable loss range. It has a function of controlling to change the overcurrent limit value by the overcurrent suppressing circuit 30 according to the detected value.

FIG. 2 shows the magnitude of the output current Ioc in the output circuit section of FIG. 1 and VCE = (VIN-Vo) of the output transistor 2.
(∵VCE >> VR17, VR17 is a characteristic diagram showing the relationship of magnitude of the voltage drop in the resistance element 17 for detection).

Here, the shaded area surrounded by the solid line shows the safe operating area SOA, and the characteristic of the conventional example is shown by the dotted line for comparison.

In the safe operating area SOA, the slope of the slope S where VCE decreases linearly from the maximum value (VIN-Vo) max to about the base-emitter voltage VBE of the transistor as Ioc increases will be described in detail later. As shown in the following equation.

-R14 * R17 / (R16 + R17) Here, R17 is a resistance value of the detection resistance element 17, and R16 is a resistance connected to one end of the detection resistance element 17 in the overcurrent suppressing circuit 30. R14 is the resistance value of the element 16, and R14 is the resistance value of the resistance element 14 whose one end is connected to the drive voltage terminal IN (the other end of the detection resistance element 17) in the VCE voltage detection control circuit 40.

According to the output circuit section shown in FIG. 1, the output transistor 2 can be controlled so as to operate reliably in the safe operation area SOA without deviating from the allowable loss range, as shown in the characteristic shown in FIG. Therefore, it is possible to prevent thermal destruction of the output transistor transistor 2 and supply a stable output voltage Vo to the load.

<Example of Basic Configuration of Overcurrent Suppression Circuit 30 and VCE Voltage Detection Control Circuit 40> Next, an example of basic configuration of the overcurrent suppression circuit 30 and VCE voltage detection control circuit 40 in FIG. 1 will be described in detail. To do.

In the overcurrent suppressing circuit 30, the current source 13 and
The collector and base were short-circuited to GND
The collector and emitter of NPN transistor 10 are connected, and NPN transistor 1 is connected to this NPN transistor 10.
1 and 12 are connected to the current mirror.

Between the drive voltage terminal IN and the collector of the NPN transistor 11, the resistor element 15 and the emitter and collector of the PNP transistor 3 whose base and collector are short-circuited are connected.
The collectors are connected in series, and the PNP transistor 3 is connected to the PNP transistor 4 as a current mirror. The PNP transistors 3 and 4 form an emitter resistor insertion type current mirror circuit 31.

The collector of the PNP transistor 4 is connected to the collector of the NPN transistor 12 and the base of the control PNP transistor 7, and the emitter of the PNP transistor 4 and the emitter of the output PNP transistor 2 (detection resistance element) are connected. The resistance element 16 is connected between the one end 17 and the other end.

In the VCE voltage detection control circuit 40, the NPN transistor in which the resistance element 14 and the collector / base are short-circuited between the drive voltage terminal IN and the output terminal OUT
8 collectors and emitters are connected in series. The NPN transistor 9 is connected to the NPN transistor 9 by current mirror connection.
The collector of 9 and the emitter of PNP transistor 4 (one end of resistance element 16) in overcurrent suppressing circuit 30 are connected.

Next, the operation of the above configuration will be described in detail.

In the overcurrent suppressing circuit 30, a current equal to the current Ia of the current source 13 is the NPN transistor 10, 11, 12, PN.
Flows to P-transistor 3. The output current Ioc is converted into a voltage value by the detection resistance element 17, and a current corresponding to this converted voltage is passed through the resistance element 16. In this case, the VCE voltage detection control circuit 40 generates a current Iy corresponding to VCE of the output transistor 2 and branches it from the current flowing through the resistance element 16. From the current flowing through this resistance element 16, the VCE voltage detection control circuit
The remaining current after subtracting the current branched to 40 flows to the PNP transistor 4 and further to the NPN transistor 12.

The base of the control transistor 7 is connected to the collector of the NPN transistor 12, and the on / off switching point of the control transistor 7 is the output current.
It becomes a threshold point that limits the overcurrent of Ioc. This threshold point is a point where the current Ia flowing through the PNP transistor 3 and the current Ik flowing through the PNP transistor 4 are equal (Ia = Ik).

Now, the output current Ioc is the overcurrent limit value Ioc (ma
In the case of (x), the voltage drop of the detection resistance element 17 becomes excessive and the current flowing through the resistance element 16 becomes small. At this time, PN
The current Ik flowing in the P-transistor 4 is
Control current PNP transistor 7 is turned on and drive circuit 1 turns off output transistor 2 so that the current flowing in NPN transistor 12 becomes equal to the current flowing in NPN transistor 11. Control.

On the other hand, when the output current Ioc is smaller than Ioc (max) and the voltage drop of the detection resistance element 17 is small, the current flowing through the resistance element 16 is large. At this time, if VCE of the output transistor 2 is also small, Iy is also small, and the current Ik flowing through the PNP transistor 4 becomes larger than the current Ia flowing through the PNP transistor 3. This allows the NPN transistor 12
Since the current Ik flowing through is larger than Ia, the control transistor 7 is off and the drive circuit 1 drives the output transistor 2 on.

On the other hand, when the output current Ioc is smaller than Ioc (max) and the current flowing through the resistance element 16 is large, if VCE of the output transistor 2 is large, Iy becomes large,
The current Ik flowing through PNP transistor 4 is
Is smaller than the current Ia flowing through it. This gives N
Set the control transistor 7 so that the current flowing through the PN transistor 12 becomes equal to the current flowing through the NPN transistor 11.
Is turned on, and the drive circuit 1 turns on the output transistor 2
Control to the off state. Therefore, the overcurrent limit value at this time becomes small.

That is, in the output circuit section of FIG. 1, for example, even when the voltage of the drive voltage terminal IN rises too much or the output voltage Vo falls too much, the output transistor 2
The magnitude of VCE, that is, the occurrence status of loss of the output transistor 2 is detected, and the output transistor 2 is detected accordingly.
The output of can be adjusted.

Therefore, according to the output circuit section of FIG.
Since current control is possible so that the output transistor 2 does not exceed its allowable loss range, that is, operates in the safe operating area SOA, the output transistor 2 deviates from the allowable loss range and is thermally destroyed ( Stable output voltage for load
It is possible to reliably prevent the possibility that Vo cannot be supplied.

Next, in the circuit of FIG. 1, the slope of the inclined portion S in the safe operation area SOA shown in FIG. 2 is obtained. In addition,
In FIG. 2, VIN-Vo (max) is the maximum rated voltage of the transistor.

Emitter resistor insertion type current mirror circuit 31
Based on the base potentials of the PNP transistors 3 and 4 that make up, the following equation (1) holds.

VT * ln (Ia / A * Is) + Ia * R15 = VT * ln (Ik / A * Is) + (Ik + Iy) * R16 + (Ik + Iy + Ioc) * R17 R15 * Ia + VT * ln (Ia / Ik) = (R16 + R17) * Ik + (R16 + R17) * Iy + R17 * Ioc (1) where A is the number of units and Is is the saturation current per unit.

Substituting the threshold point condition Ia = Ik into the above equation (1), (R16 + R17) * Iy = -R17 * Ioc- (R16 + R17-R15) * Ia (2) On the other hand, The current Iz flowing through the NPN transistor 8 is Iz = {(VCE (Tr2) + R17 * (Ik + Iy + Ioc))-VBE (Tr8)} / R14 (3). In the above formula (3), VCE (Tr2) >> R17 * (Ik + Iy + Ioc)), and the above formula (3) is Iz = {VCE (Tr2) -VBE (Tr8)} / R14 ...... (4) Becomes Iy is almost equal to Iz, and the above equation (4) is transformed into the previous equation (2).
Substituting into (R16 + R17) * {VCE (Tr2) -VBE (Tr8)} / R14 = -R17 * Ioc- (R16 + R17-R15) * Ia (R16 + R17) * VCE (Tr2) =- R14 * R17 * Ioc-R14 * (R16 + R17-R15) * Ia + (R16 + R17) * VBE (Tr8) VCE (Tr2) =-{R14 * R17 / (R16 + R17)} * Ioc + R14 * { (R15 / (R16 + R17))-1} * Ia + VBE (Tr8) (5) Constant term in the above equation (5) R14 * {(R15 / (R16 + R17))-
When 1} * Ia + VBE (Tr8) is set as A, VCE (Tr2) =-{R14 * R17 / (R16 + R17)} * Ioc + A ...... (6).

From the above equation (6), the safe operating area SO in FIG.
It can be seen that the slope of the inclined portion S at A can be determined by the resistance value R14 of the resistance element 14. In addition, from the above formulas (2) and (4), the point of VCE that lowers the overcurrent limit value that defines the safe operating area SOA from the maximum value Ioc (max) is the base-emitter voltage VBE (Tr8 of NPN transistor 8). ) Makes it possible to make a decision.

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

The output circuit portion shown in FIG. 3 is different from the output circuit portion described above with reference to FIG. 1 in the overcurrent suppressing circuit 30a and the overcurrent suppressing circuit 40a, and the other parts are the same, and therefore, in FIG. The same reference numerals are given.

The overcurrent suppressing circuit 30a in FIG. 3 is different from the overcurrent suppressing circuit 30 in FIG. 1 in that the emitter resistor insertion type current mirror circuit 31 is changed to a Wilson type current mirror circuit 32. The same parts as those in 1 are designated by the same reference numerals.

The Wilson type current mirror circuit 32 has a PN
Connect the bases of P-transistors 3 and 4 together to connect this PNP
Connect the base and collector of transistor 4 to each other.
Connect the emitter of PNP transistor 5 to the collector of PNP transistor 4 and connect the base of PNP transistor 5 to P
It is connected to the collector of NP transistor 3, and the collector of PNP transistor 5 is connected to the collector of NPN transistor 12 and the base of control transistor 7.

The VCE voltage detection control circuit 40a shown in FIG. 3 is different from the VCE voltage detection control circuit 40 shown in FIG. 1 in that (1) the resistance element 18 is inserted in series with the emitter of the NPN transistor 9;
Widlar with NPN transistors 8 and 9 and resistive element 18
(2) The emitter / base of the PNP transistor 6 between the emitter of the NPN transistor 8 of the Widlar type current source circuit 41 and the common connection node of the resistance element 18 and the output terminal OUT. Interposing a space between them and connecting the collector of this PNP transistor 6 to GND,
(3) Between the resistor element 14 and the collector of the NPN transistor 8, an arbitrary number can be used for adjusting the correction start voltage (that is, for determining how many VCE the VCE should start the correction operation by the circuit 40a). The difference is that (two in this example) Zener diodes 19 and 20 are inserted in series, and the same portions as those in FIG. 1 are denoted by the same reference numerals.

In the Widlar type current source circuit 41, R18 *
Iy = VT * ln (Iz / Iy) and the current division ratio Z = Iz / Iy.

Also in the output circuit section of FIG. 3, the on / off switching point of the control transistor 7 becomes a threshold point for limiting the overcurrent of the output current Ioc,
This point is the current Ia flowing in the PNP transistor 3 and
This is a point where the currents Ik flowing through the PNP transistor 4 are equal (Ia = Ik).

The change point (1) makes it possible to realize the small current Iy, and the change point (2) suppresses the influence of the VCE voltage detection control circuit 40a on the output current Ioc and also reduces the resistance. The resistance value of the element 14 can be reduced, and the change point (3) can increase the point of VCE at which the overcurrent limit value is lowered below the maximum value Ioc (max).

FIG. 4 shows the magnitude of the output current Ioc and VCE = (VIN of the output PNP transistor 2 in the output circuit of FIG.
It is a characteristic view showing the relationship of the magnitude of -Vo).

Here, the shaded area surrounded by the solid line shows the safe operation area SOA, and the characteristic of the conventional example is shown by the dotted line for comparison.

In the safe operation area SOA, the slope of the slope S where VCE linearly decreases from the maximum value (VIN-Vo) max to 2 * VBE + 2 * Vz as Io increases will be described later. Is expressed by the following equation.

-Z * R14 * R17 / (R16 + R17) where Z is the current division ratio in the Widlar type current mirror circuit 41, R17 is the resistance value of the detection resistance element 17, and R16 is the overcurrent. Resistor element for detection in suppression circuit 30a
The resistance value of the resistance element 16 connected to one end of 17,
R14 is the drive voltage terminal in the VCE voltage detection control circuit 40a.
This is the resistance value of the resistance element 14 whose one end is connected to IN similarly to the detection resistance element 17.

Next, in the circuit of FIG. 3, the slope of the inclined portion S in the safe operation area SOA shown in FIG. 4 is obtained. In addition,
In FIG. 4, VIN-Vo (max) is the maximum rated voltage of the transistor.

Constructing a Wilson type current mirror circuit 32
Based on the base potential of PNP transistors 3 and 4,
The following expression (7) is established.

VT * ln (Ia / A * Is) + Ia * R15 = VT * ln (Ik / A * Is) + (Ik + Iy) * R16 + (Ik + Iy + Ioc) * R17 R15 * Ia + VT * ln (Ia / Ik) = (R16 + R17) * Ik + (R16 + R17) * Iy + R17 * Ioc (7) where A is the number of units and Is is the saturation current per unit.

Substituting the condition Ia = Ik of the threshold point into the above equation (8), (R16 + R17) * Iy = -R17 * Ioc- (R16 + R17-R15) * Ia (8) On the other hand, The current Iz flowing through the NPN transistor 8 is Iz = {(VCE (Tr2) + R17 * (Ik + Iy + Ioc))-(2 * VBE + 2 * Vz)} / R14 (9). In the above formula (9), VCE (Tr2) >> R17 * (Ik + Iy + Ioc), and the above formula (9) is Iz = {VCE (Tr2)-(2 * VBE + 2 * Vz)} / R14… … (10) Z * Iy is almost equal to Iz, and if the above equation (10) is substituted into the previous equation (8), (R16 + R17) * {VCE (Tr2)-(2 * VBE + 2 * Vz)} / (R14 * Z) =-R17 * Ioc- (R16 + R17-R15) * Ia (R16 + R17) * VCE (Tr2) / Z = -R14 * R17 * Ioc-R14 * (R16 + R17-R15) * Ia + (R16 + R17) * 2 * (VBE + Vz) / Z VCE (Tr2) / Z =-{R14 * R17 / (R16 + R17)} * Ioc + R14 * {(R15 / (R16 + R17))-1} * Ia + 2 * (VBE + Vz) / Z becomes (11). Constant term in the above equation (11) R14 * ((R15 / (R16 + R17))-
If 1} * Ia is A and the constant term 2 * (VBE + Vz) is B, VCE (Tr2) =-Z * {R14 * R17 / (R16 + R17)} * Ioc + Z * A + B…. … (12)

From the above equation (12), the safe operation area SO in FIG.
It can be seen that the slope of the inclined portion S at A can be determined by the resistance value R14 of the resistance element 14. Also, from the above equations (8) and (10), the VCE point at which the overcurrent limit value that defines the safe operating area SOA falls below the maximum value Ioc (max) can be changed by the Zener voltage Vz of the Zener diodes 19 and 20. It turns out that is possible.

In the above equation (12), the constant term 2 * (VBE
The temperature characteristic of VBE in (+ Vz) is negative, but the temperature characteristic of Vz is positive, so that the temperature characteristics of both can be canceled out (temperature characteristic correction effect).

<Modification of Second Embodiment> A modification of the overcurrent suppressing circuit 30a and the VCE voltage detection control circuit 40a shown in FIG. 3 will be described.

Output current by VCE voltage detection control circuit 40a
In order to suppress the influence on Ioc, the PNP transistor 6
You may connect two or more Darlingtons.

Further, in order to change the VCE point at which the overcurrent limit value that defines the safe operating area SOA falls below the maximum value Ioc (max) in accordance with the characteristics of the output transistor 2, the VCE voltage detection control circuit The Zener diodes 19 and 20 in 40a may be omitted or the number thereof may be changed. However, the temperature characteristic correction effect due to the relationship of B = 2 * (VBE + Vz) in the above equation (12) cannot be obtained.

In the circuits of FIGS. 1 and 3, it is possible to change the polarities of the PNP transistor and the NPN transistor and to change the height relationship between the drive voltage VIN and GND.

Further, although the bipolar transistor is used as the output element in this example, the present invention is also applicable to the case where the MOSFET or the IGBT is used as the output element.

[0068]

As described above, according to the present invention, whether or not the output transistor is operating in the safe operation area is detected, and there is a possibility that the output transistor may deviate from the allowable loss range and be thermally destroyed. It is possible to provide a power semiconductor device having an overcurrent suppressing circuit that can be prevented.

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram showing the relationship between the magnitude of the output current Ioc and the magnitude of VCE = (VIN-Vo) of the output transistor in the output circuit section of FIG.

FIG. 3 is a circuit diagram showing an output circuit section of a power IC according to a second embodiment of the present invention.

4 is a characteristic diagram showing the relationship between the magnitude of the output current Ioc and the magnitude of VCE = (VIN-Vo) of the output transistor in the output circuit section of FIG.

FIG. 5 is a circuit diagram showing a conventional example of an output circuit section of a power IC using PNP transistors as output elements.

6 is a characteristic diagram showing the relationship between the magnitude of the output current Ioc and the magnitude of VCE = (VIN-Vo) of the output transistor in the output circuit section of FIG.

[Explanation of symbols]

IN… Drive voltage terminal, OUT… Output terminal, 1… Drive circuit, 2… PNP transistor for output, 3,4,5… PNP transistors, 6… PNP transistor, 7… PNP transistor for control, 8,9,10,11,12… NPN transistor, 13 ... current source, 14,15,16,18 ... Resistance element, 17 ... Resistance element for detection, 19, 20 ... Zener diode, 30a ... Overcurrent suppression circuit, 32 ... Wilson type current mirror circuit, 40a… VCE Voltage detection control circuit. 41… Widlar type current source circuit.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5J091 CA57 FA04 FP02 FP05 GP02                       HA08 HA20 HA25 KA05 KA09                       KA28 MA21 TA02 UW08                 5J500 AC57 AF04 AH08 AH20 AH25                       AK05 AK09 AK28 AM21 AT02                       PF02 PF05 PG02 WU08

Claims (7)

[Claims] 1. An output transistor in which two electrodes are connected between a drive voltage terminal to which a drive voltage is applied and an output terminal from which an output voltage is taken out, and a control electrode is drive-controlled by a drive circuit; An output current detection circuit for detecting an output current of a transistor, a two-electrode voltage detection circuit for detecting a two-electrode voltage of the output transistor, and an output current of the output current according to a detection value by the two-electrode voltage detection circuit. An electric power semiconductor device, comprising: an overcurrent suppressing circuit that controls an overcurrent limit value. 2. An output transistor in which two electrodes are connected between a drive voltage terminal to which a drive voltage is applied and an output terminal from which an output voltage is taken out, and a control electrode is drive-controlled by a drive circuit, and the drive voltage. A detection resistance element that is inserted and connected between a terminal and one end of the output transistor and through which the same output current as the output transistor flows, and the detection resistance element, wherein the output current is converted to a voltage by the detection resistance element. Value is converted into a value, and based on this converted voltage, it is detected whether or not the output current has reached an overcurrent limit value, and in the case of an overcurrent state, the drive circuit controls the output transistor to be in an off state. And an overcurrent suppressing circuit for detecting the voltage between two electrodes of the output transistor, and the detected value is a range in which the output transistor deviates from its allowable loss range. In the case of a power supply, a two-electrode voltage detection circuit is controlled to change the overcurrent limit value by the overcurrent suppression circuit according to the detected value so as not to exceed the allowable loss range. Semiconductor device. 3. An output transistor having two electrodes connected between a drive voltage terminal to which a drive voltage is applied and an output terminal from which an output voltage is taken out, and a drive circuit for driving and controlling a control electrode of the output transistor. And a control transistor connected between a control terminal for controlling the operation of the drive circuit and a ground potential, and a detection resistance element inserted and connected between the drive voltage terminal and one end of the output transistor. A resistance element for current branching connected to one end of the detection resistance element on the output transistor side; and a voltage between two electrodes of the output transistor is detected, and a current corresponding to the detected value is detected for the current branching. By branching from the current flowing through the resistance element, the remaining current of the current flowing through the current branching resistance element is allowed by the voltage between the two electrodes of the output transistor. A two-electrode voltage detection circuit for controlling to a value that takes loss into consideration, the detection resistance element, a control transistor, and a resistance element for current branching, and the remaining portion of the current flowing through the resistance element for current branching. Is compared with a reference current to detect whether or not the output current is in an overcurrent state in which the allowable loss of the voltage between the two electrodes of the output transistor is taken into consideration. When the detection result is the overcurrent state, A power semiconductor device, comprising: an overcurrent suppressing circuit which controls the control transistor to control the output transistor to be in an off state by the drive circuit. 4. The output transistor is a PNP transistor, and the overcurrent suppression circuit includes a detection resistance element inserted and connected between a drive voltage terminal and an emitter of the output transistor, a current source and a ground. First NP with collector-emitter connected to the potential and collector-base short-circuited
An N-transistor, a second NPN transistor and a third NPN transistor current-mirror connected to the first NPN transistor, and a first NPN transistor inserted between the drive voltage terminal and the collector of the second NPN transistor. The first PNP transistor, in which the emitter and collector are connected in series and the base and collector are short-circuited to each other, and the first PNP transistor is current-mirror connected to the first PNP transistor, and the collector is the second A second PNP transistor connected to the collector of the NPN transistor, and a base connected to the collector of the second PNP transistor, and an emitter-collector between a control terminal for controlling the operation of the drive circuit and the ground potential. Control PN connected between
4. A P-transistor and a second resistance element connected between the emitter of the second PNP transistor and the emitter of the output transistor. The power semiconductor device according to item 1. 5. The output transistor is a PNP transistor, and the overcurrent suppressing circuit includes a detection resistance element inserted and connected between a drive voltage terminal and an emitter of the output transistor, a current source and a ground. First NP with collector-emitter connected to the potential and collector-base short-circuited
An N-transistor, a second NPN transistor and a third NPN transistor current-mirror connected to the first NPN transistor, and a first NPN transistor inserted between the drive voltage terminal and the collector of the second NPN transistor. A first resistance element and a first PNP transistor having an emitter and a collector connected in series to the first resistance element, and a second PNP having a current mirror connection to the first PNP transistor and a base and a collector short-circuited to each other.
A transistor and a third PNP transistor whose emitter is connected to the collector of the second PNP transistor, whose base is connected to the collector of the first PNP transistor, and whose collector is connected to the collector of the third NPN transistor. And a control PN whose base is connected to the collector of the third PNP transistor and whose emitter-collector is connected between a control terminal for controlling the operation of the drive circuit and a ground potential.
4. A P-transistor and a second resistance element connected between the emitter of the second PNP transistor and the emitter of the output transistor. The power semiconductor device according to item 1. 6. The output transistor is a PNP transistor, and the two-electrode voltage detection circuit comprises a third resistance element inserted between the drive voltage terminal and the output terminal and a collector connected in series with the third resistance element. The fourth with the emitters connected and the collector-base shorted together
A current mirror connection is made to the NPN transistor and the fourth NPN transistor, and its collector is the second mirror in the overcurrent suppressing circuit.
6. The power semiconductor device according to claim 4, further comprising a fifth NPN transistor connected to the emitter of the PNP transistor. 7. The output transistor is a PNP transistor, and the two-electrode voltage detection circuit includes a third resistance element having one end connected to the drive voltage terminal, and the other end of the third resistance element. One or a plurality of Zener diodes connected in series, one end side of which is connected to, a fourth NPN transistor whose collector / base is connected to the other end side of the Zener diode, and a current mirror connected to the fourth NPN transistor. The collector of which is connected to the second current collector of the overcurrent suppressing circuit.
A fifth NPN transistor connected to the emitter of the PNP transistor, and a fourth resistance element having one end connected to the emitter of the fifth NPN transistor and the other end connected to the emitter of the fourth NPN transistor. A plurality of fourth PNP transistors connected between the emitter and collector of the other end of the fourth resistance element and the ground potential and connected to the output terminal of the base, or a plurality of Darlington connected PNP transistors The power semiconductor device according to claim 4 or 5, further comprising: