Overvoltage protection circuit and semiconductor device

Abstract

To provide a step-by-step protection against overvoltage to prevent damage to a circuit element.SOLUTION: An overvoltage protection circuit 1 includes an overvoltage detection circuit 1a, a resistance value selection circuit 1b, and a clamp circuit 1c. The clamp circuit 1c includes resistors 1c1 having multiple resistance values v1, v2, v3, ..., and a transistor 1c2, and clamps the voltage Vin to a predetermined voltage within a steady-state range. The overvoltage detection circuit 1a detects whether the voltage Vin applied to the power supply terminal VCC is in an overvoltage state. The resistance value selection circuit 1b selects a predetermined resistance value from multiple resistance values depending on the overvoltage state. The transistor 1c2 is turned on by a drive current flowing on the basis of the selected resistance value, forming a current path between the power supply terminal VCC and a ground terminal and drawing current from the power supply terminal VCC.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an overvoltage protection circuit and a semiconductor device. [Background technology]

[0002] Semiconductor devices such as IPMs (Intelligent Power Modules) contain built-in semiconductor chips that include power semiconductor elements, and the control ICs that drive the semiconductor chips are equipped with an overvoltage protection function that protects the internal circuits from overvoltage.

[0003] Related technologies include, for example, a technology proposed in which an electrostatic discharge protection circuit sets a bias voltage for a transistor and a switching circuit switches the bias voltage based on the power supply state due to a surge voltage (Patent Document 1). Another technology has been proposed in which, when it is detected that the voltage of an internal node is electrostatic discharge, the electrostatic discharge current flows from the internal node to a ground node to clamp the voltage of the internal node (Patent Document 2). Another technology has been proposed in which an electrostatic discharge protection circuit switches the pull-down resistor value connected to a power transistor depending on whether the protected circuit is operating or not (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-98260 [Patent Document 2] Japanese Patent Application Publication No. 2020-155586 [Patent Document 3] Japanese Patent Publication No. 2022-180756 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an overvoltage protection circuit and a semiconductor device that provide stepwise protection against overvoltage to prevent breakdown of circuit elements. [Means for solving the problem]

[0006] To solve the above problem, an overvoltage protection circuit is provided. The overvoltage protection circuit includes an overvoltage detection circuit, a resistance value selection circuit, and a clamp circuit. The overvoltage detection circuit detects whether the voltage applied to a power supply terminal is in an overvoltage state. The resistance value selection circuit selects a predetermined resistance value from among a plurality of resistance values ​​depending on the overvoltage state. The clamp circuit clamps the voltage and includes a resistor having a plurality of resistance values ​​and a transistor that is turned on by a drive current flowing based on the selected predetermined resistance value to form a current path between the power supply terminal and a ground terminal and draws current from the power supply terminal.

[0007] Also, to solve the above problem, a semiconductor device is provided. The semiconductor device has a switching element, a drive circuit, and an overvoltage protection circuit. The switching element switches on and off based on a drive control signal to operate a load. The drive circuit includes a drive control circuit that outputs a drive control signal based on a drive signal transmitted from a control unit, and an overvoltage protection circuit. The overvoltage protection circuit has an overvoltage detection circuit, a resistance value selection circuit, and a clamp circuit. The overvoltage detection circuit detects whether a voltage applied to a power supply terminal of the drive circuit is in an overvoltage state. The resistance value selection circuit selects a predetermined resistance value from a plurality of resistance values ​​depending on the overvoltage state. The clamp circuit clamps the voltage and includes a resistor having a plurality of resistance values ​​and a transistor that is turned on by a drive current flowing based on the selected predetermined resistance value to form a current path between the power supply terminal and a ground terminal and draws current from the power supply terminal. [Effects of the Invention]

[0008] According to one aspect, it is possible to provide step-by-step protection against overvoltage to prevent damage to circuit elements. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating an example of an overvoltage protection circuit. [Figure 2] FIG. 1 is a diagram illustrating an example of the configuration of an overvoltage protection circuit according to a reference example. [Figure 3] 1 is a diagram illustrating an example of a configuration of an overvoltage protection circuit according to an embodiment of the present invention; [Figure 4] FIG. 2 is a diagram illustrating an example of a resistor. [Figure 5] 4 is a diagram for explaining an example of a first operation of the overvoltage protection circuit when an overvoltage occurs. FIG. [Figure 6] 10 is a diagram for explaining an example of a second operation of the overvoltage protection circuit when an overvoltage occurs. FIG. [Figure 7] FIG. 10 is a diagram showing an example of a waveform of a voltage that is clamped when an overvoltage occurs. [Figure 8] FIG. 2 is a diagram illustrating an example of a first configuration of an overvoltage protection circuit. [Figure 9] FIG. 10 is a diagram illustrating an example of a second configuration of the overvoltage protection circuit. [Figure 10] FIG. 1 illustrates an example of a configuration of a semiconductor system. [Figure 11] FIG. 2 is a diagram illustrating an example of a circuit configuration of a drive circuit in a semiconductor device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the present embodiment will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same configuration are designated by the same reference numerals, and redundant description may be omitted.

[0011] 1 is a diagram illustrating an example of an overvoltage protection circuit. Overvoltage protection circuit 1 includes an overvoltage detection circuit 1a, a resistance value selection circuit 1b, and a clamp circuit 1c. Clamp circuit 1c includes resistors 1c1 having a plurality of resistance values ​​v1, v2, v3, . . . and a transistor 1c2, and clamps voltage Vin to a predetermined voltage.

[0012] The overvoltage detection circuit 1a detects whether the voltage Vin applied to the power supply terminal VCC is in an overvoltage state. The resistance value selection circuit 1b selects a predetermined resistance value from among a plurality of resistance values v1, v2, v3, ··· in the resistor 1c1 according to the overvoltage state.

[0013] For example, when the overvoltage detection circuit 1a detects that the voltage Vin is in the overvoltage state st1 of the overvoltage Vo1, the resistance value selection circuit 1b selects the resistance value v1 from the resistor 1c1. Also, when the overvoltage detection circuit 1a detects that the voltage Vin is in the overvoltage state st2 of the overvoltage Vo2 (>Vo1), the resistance value selection circuit 1b selects the resistance value v2 (>v1) from the resistor 1c1. Further, when the overvoltage detection circuit 1a detects that the voltage Vin is in the overvoltage state st3 of the overvoltage Vo3 (>Vo2), the resistance value selection circuit 1b selects the resistance value v3 (>v2) from the resistor 1c1.

[0014] The transistor 1c2 is turned on by the drive current flowing based on the predetermined resistance value selected by the resistance value selection circuit 1b. For example, in the case of the overvoltage state st1, the transistor 1c2 is turned on by the drive current Ib1 flowing based on the resistance value v1. Also, in the case of the overvoltage state st2, the transistor 1c2 is turned on by the drive current Ib2 (<Ib1) flowing based on the resistance value v2. Further, in the case of the overvoltage state st3, the transistor 1c2 is turned on by the drive current Ib3 (<Ib2) flowing based on the resistance value v3.

[0015] Then, the transistor 1c2 forms a current path between the power supply terminal VCC and the ground terminal by being turned on by the drive current and draws current from the power supply terminal VCC. For example, in the case of the overvoltage state st1, the transistor 1c2 draws a current (collector current) Icr1 from the power supply terminal VCC by being turned on by the drive current Ib1. Also, in the case of the overvoltage state st2, the transistor 1c2 draws a current Icr2 (<Icr1) from the power supply terminal VCC by being turned on by the drive current Ib2. Further, in the case of the overvoltage state st3, the transistor 1c2 draws a current Icr3 (<Icr2) from the power supply terminal VCC by being turned on by the drive current Ib3.

[0016] In this way, the overvoltage protection circuit 1 selects a predetermined resistance value from among a plurality of resistance values ​​depending on the overvoltage state, turns on the transistor with a drive current that flows based on the selected predetermined resistance value, forms a current path between the power supply terminal and the ground terminal, and draws current from the power supply terminal.

[0017] This allows for adaptive switching of the dynamic resistance value when the transistor is turned on based on the magnitude of the overvoltage, providing stepwise protection against overvoltage and preventing damage to circuit elements. For example, the inrush current caused by an overvoltage condition such as ESD (Electro-Static Discharge) is prevented from flowing into the clamp circuit, preventing thermal damage to circuit elements in the clamp circuit.

[0018] Next, an overvoltage protection circuit of a reference example will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of an overvoltage protection circuit of a reference example. The overvoltage protection circuit 120 of the reference example includes Zener diodes ZD11 and ZD12, a base resistor Rb, a pull-down resistor R0, and a transistor Tr10. The transistor Tr10 is a bipolar transistor, and in this example, an NPN transistor is used.

[0019] The power supply terminal VCC is connected to the collector of transistor Tr10 and the cathode of Zener diode ZD11. The anode of Zener diode ZD11 is connected to one end of base resistor Rb and the cathode of Zener diode ZD12. The other end of base resistor Rb is connected to the base of transistor Tr10 and one end of pull-down resistor R0. The emitter of transistor Tr10 is connected to the other end of pull-down resistor R0, the anode of Zener diode ZD12, and the ground terminal (hereinafter sometimes referred to as GND).

[0020] The overvoltage protection circuit 120 is designed to protect the target circuit by clamping the voltage when an overvoltage is applied to the power supply terminal VCC. The overvoltage protection operation of the overvoltage protection circuit 120 is as follows: When an overvoltage occurs at the power supply terminal VCC, Zener diodes ZD11 and ZD12 break down and become conductive. At this time, the voltage across the junction between the anode of Zener diode ZD11 and the cathode of Zener diode ZD12 is applied to one end of base resistor Rb, causing base current Ib to flow through transistor Tr10 and turning it on.

[0021] When the transistor Tr10 is turned on, the collector current Icr flows from the collector to the emitter. fe Then, the collector current Icr is the DC current amplification factor h fe Depending on the current, a current several tens to several hundreds times the base current Ib will flow.

[0022] In this way, when an overvoltage occurs at the power supply terminal VCC, the transistor Tr10 turns on, forming a current path between the power supply terminal VCC and GND, and the overvoltage is drawn out as a current from the power supply terminal VCC. With this configuration, the voltage applied to the power supply terminal VCC is clamped to a predetermined voltage.

[0023] The pull-down resistor R0 serves to remove any charge remaining in the base of transistor Tr10, for example, immediately after restarting the device, as this can cause the transistor Tr10 to malfunction.

[0024] In the overvoltage protection circuit 120, if a steep, high-energy overvoltage, such as ESD, is applied to the power supply terminal VCC, an inrush current may flow into the base of the transistor Tr10, potentially destroying the transistor Tr10. In such a case, the entire overvoltage protection circuit 120 may be short-circuited and destroyed.

[0025] One possible measure to prevent breakdown of transistor Tr10 due to inrush current is to increase the resistance of base resistor Rb. However, if the resistance of base resistor Rb is fixed at a large value, this will result in a decrease in overvoltage protection function. Thus, in the configuration of overvoltage protection circuit 120, increasing the resistance of the base resistor prevents inrush current from flowing into the transistor, but decreases the overvoltage protection function. This trade-off makes it difficult to perform highly accurate and reliable overvoltage protection control.

[0026] Next, the overvoltage protection circuit of this embodiment will be described in detail below. Figure 3 is a diagram showing an example of the configuration of the overvoltage protection circuit of this embodiment. The overvoltage protection circuit 10 has the functions of the overvoltage protection circuit 1 shown in Figure 1, and includes an overvoltage detection switch SW and a clamp circuit 13a. The overvoltage detection switch SW is a schematic representation of the functions of the overvoltage detection circuit 1a and resistance value selection circuit 1b shown in Figure 1.

[0027] The clamp circuit 13a includes a resistor Rbv1, a Zener diode ZD1, a pull-down resistor R0, and a transistor Tr1, which is a bipolar transistor, and in this example, an NPN transistor is used.

[0028] In the following description, a voltage applied state during steady operation is defined as a state in which the voltage Vin applied to the power supply terminal VCC is less than 30 V (first voltage). The overvoltage protection circuit 10 regards a voltage Vin applied to the power supply terminal VCC of 30 V or more as an occurrence of an overvoltage, and performs two-stage overvoltage protection control according to the overvoltage state when the voltage Vin is 30 V or more but less than 40 V (second voltage) (first overvoltage state), and when the voltage Vin is 40 V or more (second overvoltage state).

[0029] The overvoltage detection switch SW includes terminal a and terminals b0, b1, and b2. One end of terminal a is connected to the power supply terminal VCC and the collector of transistor Tr1. The other end of terminal a is connected to one of terminals b0, b1, or b2 depending on the magnitude of the voltage Vin applied to the power supply terminal VCC.

[0030] Terminal b0 is connected to a subsequent circuit (not shown) to which voltage Vin applied to power supply terminal VCC is supplied. Terminal b1 is connected to point p1 (a predetermined point) of resistor Rbv1. Terminal b2 is connected to point p2 (a first end) of resistor Rbv1 and the cathode of Zener diode ZD1. Point p3 (a second end) of resistor Rbv1 is connected to the base of transistor Tr1 and one end of pull-down resistor R0. The emitter of transistor Tr1 is connected to the other end of pull-down resistor R0, the anode of Zener diode ZD1, and GND.

[0031] The overvoltage detection switch SW connects the terminal a to the terminal b0 when it detects that the voltage Vin applied to the power supply terminal VCC is less than 30 V. Since a voltage Vin less than 30 V is not an overvoltage but a voltage applied during steady operation, the overvoltage protection control by the clamp circuit 13a is not activated.

[0032] 4 is a diagram illustrating an example of a resistor. The resistor Rbv1 is a resistor made of polyimide (hereinafter, may be referred to as a polyimide resistor). The resistance value R of the polyimide resistor is calculated by the following formula (1), where ρ is the resistivity, L is the length, and S is the cross-sectional area.

[0033] R=ρ×L / S (1) Furthermore, the resistance value of the polyimide resistor can be varied depending on the length L and cross-sectional area S between the point where the current enters the polyimide resistor and the point where the current leaves the polyimide resistor.

[0034] Therefore, by adjusting the position of the point where current enters the polyimide resistor, the resistance value of the polyimide resistor between the point where the current enters and the point where the current exits can be arbitrarily changed to obtain the desired resistance value.

[0035] For example, let point p3 be the point where current is output from polyimide resistor Rbv1, and points p1 and p2 be the points where current is input to polyimide resistor Rbv1. The resistance value v1 between points p1 and p3 is determined based on the length and cross-sectional area between points p1 and p3. The resistance value v2 between points p2 and p3 is also determined by the length and cross-sectional area between points p2 and p3.

[0036] Therefore, by inputting a current to point p1 of polyimide resistor Rbv1, a resistor Rb1 with a resistance value v1 can be set between points p1 and p3. Also, by inputting a current to point p2 of polyimide resistor Rbv1, a resistor Rb2 with a resistance value v2, which is greater than v1, can be set between points p2 and p3.

[0037] 5 is a diagram illustrating an example of a first operation of the overvoltage protection circuit when an overvoltage occurs. Hereinafter, it is assumed that a resistor Rb1 with a resistance value of 100 Ω is formed from point p1 to point p3 of the resistor Rbv1, and a resistor Rb2 with a resistance value of 300 Ω is formed from point p2 to point p3 of the resistor Rbv1.

[0038] Suppose that the overvoltage detection switch SW detects that the voltage Vin applied to the power supply terminal VCC is equal to or greater than 30 V and less than 40 V. In this case, the terminal a is connected to the terminal b1. Since the voltage Vin is equal to or greater than 30 V and less than 40 V, the clamp circuit 13a is activated to perform overvoltage protection control.

[0039] When an overvoltage of 30 V or more but less than 40 V occurs at the power supply terminal VCC, the Zener diode ZD1 breaks down and becomes conductive via the resistor Rbv1. Also, because terminal a is connected to terminal b1 and current is input to point p1 of the resistor Rbv1, a resistor Rb1 with a resistance value of 100 Ω (first resistance value) is formed between points p1 and p3.

[0040] The voltage at point p1 is then applied to one end of base resistor Rb1, causing a base current Ib1 (first drive current) based on the 100Ω base resistor Rb1 to flow through transistor Tr1, turning on transistor Tr1. When transistor Tr1 turns on, a current path is formed between power supply terminals VCC and GND, causing collector current Icr1 to flow from the collector to the emitter, and the collector current Icr1 (first current) is drawn from power supply terminal VCC.

[0041] In this way, when an overvoltage of 30 V or more but less than 40 V occurs at the power supply terminal VCC, the base resistor Rb1 of 100 Ω is selected as the operating resistance of the transistor Tr1. Then, the base current Ib1 based on the base resistor Rb1 turns on the transistor Tr1, forming a current path between the power supply terminal VCC and GND, and the overvoltage is drawn out as a current from the power supply terminal VCC.

[0042] 6 is a diagram illustrating an example of a second operation of the overvoltage protection circuit when an overvoltage occurs. Suppose that the overvoltage detection switch SW detects that the voltage Vin applied to the power supply terminal VCC is 40 V or higher. In this case, terminal a is connected to terminal b2. Since the voltage Vin of 40 V or higher is being applied to the power supply terminal VCC, the clamp circuit 13a is activated to perform overvoltage protection control.

[0043] When an overvoltage of 40V or more occurs at the power supply terminal VCC, the Zener diode ZD1 breaks down and conducts. Also, since terminal a is connected to terminal b2 and current is input to point p2 of the resistor Rbv1, a resistor Rb2 with a resistance value of 300Ω (the second resistance value) is formed between point p2 and point p3.

[0044] And since the voltage applied to point p2 is applied to one end of the base resistor Rb2, a base current Ib2 (the second drive current) based on the 300Ω base resistor Rb2 flows through the transistor Tr1 (Ib2 < Ib1), and the transistor Tr1 turns on. When the transistor Tr1 turns on, a current path is formed between the power supply terminal VCC and GND, and a collector current Icr2 (< Icr1) flows from the collector to the emitter, and the collector current Icr2 (the second current) is drawn from the power supply terminal VCC.

[0045] In this way, when an overvoltage of 40V or more occurs at the power supply terminal VCC, a 300Ω base resistor Rb2 is selected as the operating resistance of the transistor Tr1. And based on the base current Ib2 based on the base resistor Rb2, the transistor Tr1 turns on and a current path is formed between the power supply terminal VCC and GND, so that the overvoltage is drawn from the power supply terminal VCC as current.

[0046] As described above, in FIGS. 1, 3, 4, 5, and 6, an embodiment of a configuration that performs two-stage overvoltage protection control according to the overvoltage state has been described, but it is not limited to two-stage control, and a configuration that performs three-stage or more control may be used.

[0047] FIG. 7 is a diagram showing an example of the waveform of the voltage clamped when an overvoltage occurs. The vertical axis is the voltage Vin applied to the power supply terminal VCC, and the horizontal axis is time. The dotted line waveform shows the waveform of the voltage Vin clamped when an overvoltage occurs in the overvoltage protection circuit 120 of the reference example. The solid line waveform shows the waveform of the voltage Vin clamped when an overvoltage occurs in the overvoltage protection circuit 10 of the present embodiment.

[0048] In the case of the overvoltage protection circuit 120, if base resistor Rb is set to a fixed high resistance value to prevent damage to circuit elements, voltage Vin rises sharply during time period T1, as shown by the dotted waveform. Subsequently, overvoltage protection control causes the overvoltage to transition to a DC state during time period T2, and then to a steady-state operating state during time period T3. However, if base resistor Rb with a fixed high resistance value is used as the operating resistance of transistor Tr10, the steep rise in ESD level during time period T1 cannot be suppressed, resulting in a degradation of the overvoltage protection function. While damage to the internal circuit elements of the overvoltage protection circuit 120 can be prevented, this may have a negative impact on the circuitry that is the intended target of overvoltage protection.

[0049] The operation of the overvoltage protection circuit 10 of this embodiment, as indicated by the solid line waveform, will be described below for each of the time periods T1, T2, and T3. [Time period T1] An overvoltage of 30 V or more is applied between the power supply terminals VCC and GND for a short period of time. In this case, the overvoltage protection circuit 10 operates as shown in Figure 5. Therefore, when an overvoltage of 30 V or more (for example, an overvoltage of 30 V or more that lasts for 10 nsec or more) occurs, the overvoltage protection circuit 10 selects 100 Ω as the resistance value of the base resistor of transistor Tr1, turns on transistor Tr1 with this low resistance value of 100 Ω, and draws the overvoltage as a current from the power supply terminal VCC.

[0050] [Time period T2] If transistor Tr1 is turned on with a base resistance of 100 Ω and current continues to be drawn from power supply terminal VCC (for example, for 1 μsec or more), and the overvoltage continues to rise, there is a risk of thermal destruction of transistor Tr1. For this reason, when an overvoltage state of 40 V or more occurs between power supply terminals VCC and GND, the overvoltage protection circuit 10 transitions from the operating state shown in Figure 5 to the operating state shown in Figure 6.

[0051] Therefore, the overvoltage protection circuit 10 selects 300Ω as the resistance value of the base resistor of the transistor Tr1, turns on the transistor Tr1 with the high resistance value of 300Ω, and draws the overvoltage as a current from the power supply terminal VCC.

[0052] This reduces the current drawn by transistor Tr1, preventing thermal damage to transistor Tr1 (the amount of current drawn from power supply terminal VCC is reduced). Also, the rise in voltage Vin is suppressed, resulting in a DC state (smooth state).

[0053] [Time period T3] This is the period during which the protection operation of the overvoltage protection circuit 10 ends. By extracting the overvoltage as current from the power supply terminal VCC, the energy of the overvoltage (energy of the surge voltage) is consumed. This eliminates the overvoltage state of the voltage Vin applied to the power supply terminal VCC, and the overvoltage protection circuit 10 transitions to the operating state shown in FIG. 3 and enters a steady operating state (for example, a steady operating state around 15 V).

[0054] As described above, the overvoltage protection circuit 10 is configured to switch the resistance value of the base resistor, which is the operating resistance of the transistor Tr1, depending on the magnitude of the overvoltage applied to the power supply terminal VCC. In the above example, a base resistor value of 100 Ω is selected when the overvoltage is 30 V or more but less than 40 V, and a base resistor value of 300 Ω is selected when the overvoltage is 40 V or more.

[0055] Therefore, when an overvoltage such as ESD of 40V or more is applied to the power supply terminal VCC, a base resistor with a high resistance is selected, so that an inrush current does not flow into the base of transistor Tr1, preventing thermal damage to transistor Tr1 due to the inrush current. Furthermore, after preventing thermal damage to transistor Tr1 due to the inrush current, the base current flowing through the high-resistance base resistor turns on transistor Tr1, clamping the overvoltage to a predetermined voltage.

[0056] Furthermore, when an overvoltage of 30 V or more but less than 40 V is applied to the power supply terminal VCC, a base resistor with a low resistance is selected, and transistor Tr1 turns on due to the base current flowing through the low-resistance base resistor, allowing the overvoltage to be clamped to a predetermined voltage without degrading the overvoltage detection function.

[0057] Therefore, in the overvoltage protection circuit 10, in an overvoltage state of 40 V or more, the resistance value of the base resistor is switched from a low resistance value to a high resistance value, suppressing the input of inrush current and preventing damage to circuit elements, and in an overvoltage state of 30 V or more but less than 40 V, a low resistance value is selected for the resistance value of the base resistor and overvoltage protection control is performed, thereby preventing a deterioration in the overvoltage protection function.

[0058] In this way, the overvoltage protection circuit 10 performs step-by-step overvoltage protection by varying the resistance value of the base resistor according to the magnitude of the overvoltage, thereby making it possible to both prevent breakdown of circuit elements and suppress deterioration of the overvoltage protection function. This improves the above-mentioned trade-off relationship and makes it possible to achieve highly accurate and reliable overvoltage protection control.

[0059] Next, the configuration of the overvoltage protection circuit of this embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is a diagram showing an example of a first configuration of an overvoltage protection circuit. The overvoltage protection circuit 10a includes an overvoltage detection circuit 11, a resistance value selection circuit 12-1 (first resistance value selection circuit), a resistance value selection circuit 12-2 (second resistance value selection circuit), and a clamp circuit 13a. The overvoltage detection circuit 11 and the resistance value selection circuits 12-1 and 12-2 implement the function of the overvoltage detection switch SW shown in FIGS. 3, 5, and 6. The configuration of the clamp circuit 13a has been described above, so a description thereof will be omitted.

[0060] The overvoltage detection circuit 11 includes a comparator cmp1 (first comparator), a comparator cmp2 (second comparator), a resistor R1 (first voltage dividing resistor), a resistor R2 (second voltage dividing resistor), a resistor R3 (third voltage dividing resistor), a resistor R4 (fourth voltage dividing resistor), a reference voltage source ref1 (first reference voltage source), a reference voltage source ref2 (second reference voltage source), a two-input, one-output AND element (logical product element) 11a, and an inverter element 11b.

[0061] The resistance value selection circuit 12-1 includes a transistor Trs1 (first transistor) and a base resistor Rbs1 (first base resistor), and the resistance value selection circuit 12-2 includes a transistor Trs2 (second transistor) and a base resistor Rbs2 (second base resistor). The transistors Trs1 and Trs2 are bipolar transistors, and in this example, NPN transistors are used.

[0062] The power supply terminal VCC is connected to the collector of transistor Tr1, one end of resistor R1, the collector of transistor Trs1, one end of resistor R3, and the collector of transistor Trs2. The other end of resistor R1 is connected to one end of resistor R2 and the non-inverting input terminal (+) of comparator cmp1. The inverting input terminal (-) of comparator cmp1 is connected to the positive terminal of reference voltage source ref1, and the negative terminal of reference voltage source ref1 is connected to the other end of resistor R2 and GND.

[0063] The output terminal of the comparator cmp1 is connected to one input terminal of an AND element 11a. The other input terminal of the AND element 11a is connected to the output terminal of the inverter element 11b. The output terminal of the AND element 11a is connected to one end of a base resistor Rbs1, and the other end of the base resistor Rbs1 is connected to the base of a transistor Trs1. The emitter of the transistor Trs1 is connected to point p1 of the resistor Rbv1.

[0064] Meanwhile, the other end of resistor R3 is connected to one end of resistor R4 and the non-inverting input terminal (+) of comparator cmp2. The inverting input terminal (-) of comparator cmp2 is connected to the positive terminal of reference voltage source ref2, and the negative terminal of reference voltage source ref2 is connected to the other end of resistor R4 and GND.

[0065] The output terminal of the comparator cmp2 is connected to one end of a base resistor Rbs2, the other end of which is connected to the input terminal of the inverter element 11b and the base of a transistor Trs2, the emitter of which is connected to point p2 of the resistor Rbv1 and the cathode of a Zener diode ZD1.

[0066] Here, the voltage Vin applied to the power supply terminal VCC is divided by resistors R1 and R2 to become a voltage Vd1 (first voltage), which is input to the non-inverting input terminal (+) of the comparator cmp1. Also, the reference voltage source ref1 outputs a reference voltage Vr1 (first reference voltage), and the reference voltage Vr1 is input to the inverting input terminal (-) of the comparator cmp1.

[0067] When the voltage Vin is 30 V or higher, the voltage Vd1 is equal to or higher than the reference voltage Vr1, and an H-level signal is output from the output terminal of the comparator cmp1. When the voltage Vin is less than 30 V, the voltage Vd1 is less than the reference voltage Vr1, and an L-level signal is output from the output terminal of the comparator cmp1.

[0068] For example, when a voltage Vd1 is generated by dividing the voltage Vin by half using resistors R1 and R2 and input to the non-inverting input terminal (+) of the comparator cmp1, the reference voltage source ref1 is set to output a reference voltage Vr1 of 15V (=30V / 2).

[0069] Meanwhile, the voltage Vin applied to the power supply terminal VCC is divided by resistors R3 and R4 to become a voltage Vd2 (second voltage), which is input to the non-inverting input terminal (+) of the comparator cmp2. Also, the reference voltage source ref2 outputs a reference voltage Vr2 (second reference voltage), which is input to the inverting input terminal (-) of the comparator cmp2. The reference voltage Vr2 is set to a value greater than the reference voltage Vr1.

[0070] When the voltage Vin is 40 V or higher, the voltage Vd2 is equal to or higher than the reference voltage Vr2, and an H-level signal is output from the output terminal of the comparator cmp2. When the voltage Vin is less than 40 V, the voltage Vd2 is less than the reference voltage Vr2, and an L-level signal is output from the output terminal of the comparator cmp2.

[0071] For example, if a voltage Vd2 is generated by dividing the voltage Vin by half using resistors R3 and R4 and input to the non-inverting input terminal (+) of the comparator cmp2, ​​the reference voltage source ref2 is set to output a reference voltage Vr2 of 20V (=40V / 2).

[0072] Here, when the voltage Vin is less than 30 V, the comparator cmp1 outputs an L-level signal, and the comparator cmp2 outputs an L-level signal, so that both the transistors Trs1 and Trs2 are turned off and the clamp circuit 13a is not driven.

[0073] Furthermore, when the voltage Vin reaches an overvoltage state of 30 V or more but less than 40 V, the comparator cmp1 outputs an H-level signal, and the comparator cmp2 outputs an L-level signal. Therefore, the transistor Trs2 is turned off. Meanwhile, the L-level signal output from the comparator cmp2 is inverted by the inverter element 11b to become an H-level signal, which is input to the other input terminal of the AND element 11a.

[0074] Therefore, an H-level signal is output from the output terminal of the AND element 11a, turning on the transistor Trs1. That is, because the transistor Trs1 is turned on and the transistor Trs2 is turned off, a current flows through the point p1 of the resistor Rbv1, and in an overvoltage state of 30 V or more but less than 40 V, a resistance value of 100 Ω (resistor Rb1) is selected.

[0075] When the voltage Vin reaches an overvoltage state of 40 V or more, the comparator cmp1 outputs an H-level signal, and the comparator cmp2 outputs an H-level signal. The H-level signal output from the comparator cmp2 turns on the transistor Trs2, and the H-level signal output from the comparator cmp2 is inverted by the inverter element 11b to become an L-level signal, which is input to the other input terminal of the AND element 11a.

[0076] Therefore, an L-level signal is output from the output terminal of the AND element 11a, turning off the transistor Trs1. That is, the transistor Trs1 turns off and the transistor Trs2 turns on, causing current to flow through the point p2 of the resistor Rbv1, and in an overvoltage state of 40 V or more, a resistance value of 300 Ω (resistor Rb2) is selected.

[0077] 9 is a diagram showing an example of a second configuration of an overvoltage protection circuit. Overvoltage protection circuit 10b includes overvoltage detection circuit 11, resistance value selection circuits 12-1 and 12-2, and clamp circuit 13b. The configurations of overvoltage detection circuit 11 and resistance value selection circuits 12-1 and 12-2 are the same as those in FIG. 8.

[0078] The clamp circuit 13b includes a resistor Rbv2, a Zener diode ZD1, a pull-down resistor R0, and a transistor Tr1. The clamp circuit 13b includes a resistor Rbv2 instead of the resistor Rbv1. The resistor Rbv2 includes a resistor Rb11 (first resistor) having a resistance value of 100 Ω and a resistor Rb12 (second resistor) having a resistance value of 200 Ω.

[0079] The cathode of Zener diode ZD1 is connected to one end of resistor Rb11, one end of resistor Rb12, and the emitter of transistor Trs1. The other end of resistor Rb12 is connected to the emitter of transistor Trs2. The other end of resistor Rb11 is connected to one end of pull-down resistor R0 and the base of transistor Tr1. The emitter of transistor Tr1 is connected to the other end of pull-down resistor R0, the anode of Zener diode ZD1, and GND. The collector of transistor Tr1 is connected to power supply terminal VCC.

[0080] If the voltage Vin falls into an overvoltage state of 30V or more but less than 40V, as described above, transistor Trs1 turns on and transistor Trs2 turns off. Therefore, a resistance value of 100Ω (resistor Rb11) is selected for resistor Rbv2. Therefore, a drive current Ib1 based on resistor Rb11 is input to the base of transistor Tr1, turning transistor Tr1 on and drawing current Icr1 from power supply terminal VCC.

[0081] Furthermore, when voltage Vin reaches an overvoltage state of 40 V or higher, transistor Trs1 turns off and transistor Trs2 turns on, as described above. Therefore, a resistance value of 300 Ω, which is the combined series resistance of resistors Rb11 and Rb12 (100 Ω and 200 Ω), is selected for resistor Rbv2. Therefore, drive current Ib2 based on the combined series resistance of resistors Rb11 and Rb12 is input to the base of transistor Tr1, turning transistor Tr1 on and drawing current Icr2 from power supply terminal VCC.

[0082] In this way, by using resistors Rb11 and Rb12 such as general-purpose carbon film resistors instead of polyimide resistors, it is possible to similarly perform stepwise overvoltage protection control according to the magnitude of the overvoltage by varying the resistance value, as described above in Figures 3, 5, and 6.

[0083] Next, a semiconductor device to which the overvoltage protection circuit 10 is applied will be described with reference to FIGS. 10 and 11. FIG. 10 is a diagram showing an example of the configuration of a semiconductor system. A semiconductor system 200 is connected to a load 210 and switches on and off a current supplied to the load 210. The semiconductor system 200 may function as a power conversion device such as a motor drive inverter or a DC-DC converter. The semiconductor system 200 includes a semiconductor device 100, a control unit 110, a power supply 130, a capacitor 140, and a current detection resistor 150.

[0084] The semiconductor device 100 is an IPM used to supply power to a power-consuming load 210. The semiconductor device 100 includes high-side drive units 60 (60a, 60b, 60c), a low-side drive unit 20, high-side switching elements 30 (30a, 30b, 30c), high-side diodes 35 (35a, 35b, 35c), low-side switching elements 40 (40a, 40b, 40c), low-side diodes 45 (45a, 45b, 45c), and bootstrap units 50 (50a, 50b, 50c).

[0085] The high-side switching element 30 and the low-side switching element 40 switch on and off the current supplied to the load 210. The high-side switching element 30 and the low-side switching element 40 are voltage-driven switching elements, and an example of such switching elements is an IGBT (Insulated Gate Bipolar Transistor). Alternatively, the switching elements may be power MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), or may be made of a wide-gap semiconductor such as SiC, GaN, diamond, a gallium nitride-based material, a gallium oxide-based material, AlN, AlGaN, or ZnO.

[0086] The high-side switching element 30 is provided between the positive terminal P and the output terminals U, V, and W of each phase. The high-side switching element 30 switches whether or not the positive terminal P and the load 210 are connected, depending on the gate voltage input to the gate terminal.

[0087] The low-side switching element 40 is provided between the negative terminals N(U), N(V), N(W) and the output terminals U, V, W of each phase. The low-side switching element 40 switches whether or not the negative terminals N(U), N(V), N(W) and the load 210 are connected, depending on the gate voltage input to the gate terminal.

[0088] The high-side diode 35 is a free wheel diode (FWD) for commutating the load current from the load 210. The high-side diode 35 is connected in parallel to the high-side switching element 30. The high-side diode 35 may be made of a wide-gap semiconductor, or may be realized by a parasitic diode when the high-side switching element 30 is a MOSFET. The high-side switching element 30 and the high-side diode 35 form an upper arm (high-voltage side arm).

[0089] Similarly, low-side diode 45 is connected in parallel to low-side switching element 40 and is an FWD for commutating the load current from load 210. Low-side diode 45 may be made of a wide-gap semiconductor, or may be realized by a parasitic diode when low-side switching element 40 is a MOSFET. Low-side switching element 40 and low-side diode 45 form a lower arm (low-voltage side arm).

[0090] The node connecting the emitter terminal of the upper arm and the collector terminal of the lower arm is connected to the output terminals U, V, and W of each phase. The collector terminal of the upper arm is connected to the positive terminal P of each phase. In this example, the collector terminal of the upper arm is connected to the common positive terminal P. The emitter terminal of the lower arm is connected to the negative terminals N(U), N(V), and N(W) of each phase, respectively. The upper arm and lower arm of each phase form a half-bridge circuit.

[0091] The negative terminals N(U), N(V), and N(W) are connected to a terminal 107, which is a common negative terminal interconnected outside the semiconductor device 100. A power supply 130, which is a DC power supply for output, is connected between the positive terminal P and the terminal 107.

[0092] The high-side driver 60 is an HVIC (High Voltage IC) that drives the high-side switching element 30 of the upper arm to switch the high-side switching element 30 on and off. The high-side driver 60 supplies a gate voltage corresponding to a gate control input signal from the controller 110 to the gate terminal of the high-side switching element 30 to control the on and off of the high-side switching element 30. The semiconductor device 100 of this example includes three high-side drivers 60a, 60b, and 60c corresponding to the respective phases.

[0093] The high-side driver 60 is connected to the gate terminal and emitter terminal of the corresponding high-side switching element 30. The gate terminal of the high-side switching element 30 is connected to the gate output terminal OUT of the corresponding high-side driver 60. The emitter terminal of the high-side switching element 30 is connected to the reference potential terminal V of the corresponding high-side driver 60. S The high-side driver 60 is connected to the gate output terminal OUT and the reference potential terminal V S By controlling the voltage between the terminals, the conduction and cutoff between the collector and the emitter of the corresponding high-side switching element 30 is controlled.

[0094] As a result, the high-side drivers 60a, 60b, and 60c switch on and off the high-side switching elements 30a, 30b, and 30c of the U, V, and W phases, respectively. The high-side driver 60 is connected to the emitter terminal of the high-side switching element 30 and has a reference potential terminal V S The reference potential of the high-side driver 60 is the potential on the emitter side of the corresponding high-side switching element 30.

[0095] Since the high-side drivers 60a, 60b, and 60c have different reference potentials for operation, they are configured as independent driver ICs for each phase. Therefore, if an independent reference potential is provided for each phase within the IC, the high-side drivers 60a, 60b, and 60c may be integrated into a single IC.

[0096] The low-side driver 20 is an LVIC (Low Voltage IC) that drives the low-side switching element 40 of the lower arm and switches on and off the low-side switching element 40. The low-side driver 20 supplies a gate voltage corresponding to a gate control input signal from the control unit 110 to the gate terminal of the low-side switching element 40 to control the on and off of the low-side switching element 40.

[0097] The low-side driver 20 of this example is connected to three low-side switching elements 40a, 40b, and 40c. The low-side driver 20 has three gate output terminals (U OUT , V OUT , W OUT ) and connected to the gate terminals of the three low-side switching elements 40a, 40b, and 40c, respectively.

[0098] The low-side driver 20 is also connected to an overcurrent detection external terminal IS, and receives the sense voltage detected by the current detection resistor 150. When the sense voltage is higher than a threshold, the low-side driver 20 detects that an overcurrent is flowing through the low-side switching elements 40a, 40b, and 40c. In response to the detection of the overcurrent, the low-side driver 20 performs a protective operation, such as switching off the low-side switching elements 40a, 40b, and 40c.

[0099] The low-side drive unit 20 is connected to the low-side power supply terminal V CCL Power supply voltage input terminal V connected to CC and a terminal GND connected to the common ground terminal COM, and a power supply voltage input terminal V CC It operates using the voltage between this pin and the GND pin as the power supply voltage.

[0100] The emitter terminal of the low-side switching element 40 is connected to the common ground terminal COM via the current detection resistor 150. That is, the low-side driver 20 operates with the potential on the emitter side of the low-side switching elements 40a, 40b, and 40c as the reference potential. The low-side driver 20 is connected to the gate output terminal (UOUT , V OUT , W OUT The on / off of the low-side switching element 40 is controlled by controlling the inter-terminal voltage between the low-side switching element 40 and the terminal GND.

[0101] The control unit 110 is a microcontroller that controls the driving of the semiconductor device 100. The control unit 110 generates gate control input signals to rotate the motor, which is the load 210, at a predetermined rotation speed, and supplies the signals to the high-side drive units 60a, 60b, and 60c and the low-side drive unit 20 via drive signal input terminals IN(HU), IN(HV), IN(HW), IN(LU), IN(LV), and IN(LW). For example, the control unit 110 controls each gate control input signal by PWM (Pulse Width Modulation) control.

[0102] The load 210 is a three-phase motor having three phases: U phase, V phase, and W phase. The semiconductor device 100 may have half-bridge circuits in a number corresponding to the number of phases of the motor. The bootstrap section 50 is connected to the high-side power supply terminal V CCH The power supply voltage from the power supply 140 acts as a bootstrap diode (BSD) used to charge the capacitor 140.

[0103] The bootstrap section 50 is connected to the high-side power supply terminal V CCH and high-side drive external terminal V B The bootstrap unit 50 is disposed between the high-side drive external terminal V B and power supply voltage input terminal V CC is connected between

[0104] The capacitor 140 is charged via the bootstrap unit 50 and operates the high-side drive unit 60. The capacitor 140 functions as a bootstrap capacitor (BSC) for boosting the power supply voltage of the high-side drive unit 60. The capacitor 140 is connected to the high-side drive external terminal VB The power supply voltage is supplied to the high side driver 60 of each phase via the

[0105] Capacitor 140a is connected between the high side drive external terminal VB(U) and the output terminal U, and is charged by the bootstrap unit 50a. Capacitor 140b is connected between the high side drive external terminal VB(V) and the V terminal, and is charged by the bootstrap unit 50b. Capacitor 140c is connected between the high side drive external terminal VB(W) and the W terminal, and is charged by the bootstrap unit 50c. Capacitors 140a, 140b, and 140c supply power supply voltages to high side drive units 60a, 60b, and 60c, respectively.

[0106] The current detection resistor 150 is connected between the terminal 107 and the reference potential 105. The current detection resistor 150 is connected to the outside of the semiconductor device 100 so that the current detection resistor 150 can be changed according to a circuit externally connected to the semiconductor device 100. The current detection resistor 150 may also be built into the semiconductor device 100.

[0107] In the semiconductor device 100, the high-side switching elements 30 are turned on at different timings for each phase, so there is no time when two or more of the plurality of low-side switching elements 40 are turned on simultaneously. Therefore, the low-side driver 20 can perform overcurrent detection for the low-side switching elements 40 for three phases using one current detection resistor 150.

[0108] Here, low-side driver 20 has the function of detecting the current flowing through the half-bridge circuit of each phase using current detection resistor 150 and protecting the module when an overcurrent occurs. The current level signal detected by current detection resistor 150 is transmitted to low-side driver 20 via overcurrent detection external terminal IS. Low-side driver 20 determines whether an overcurrent exists, and when an overcurrent occurs, it shuts off low-side switching element 40 to protect the lower arm.

[0109] Meanwhile, the high-side driver 60 receives a current level signal detected by the current detection resistor 150 and transmits it to the control unit 110. When an overcurrent occurs, the high-side driver 60 protects the upper arm by shutting off the high-side switching element 30 based on the overcurrent determination by the control unit 110. Then, the control unit 110 performs the overcurrent determination by program processing.

[0110] 11 is a diagram showing an example of the circuit configuration of a drive circuit in a semiconductor device. A semiconductor device 100-1 is an equivalent circuit inside the semiconductor device 100 shown in FIG. The semiconductor device 100-1 includes an HVIC 60-1, an LVIC 20-1, a bootstrap unit 50-1, a high-side switching element 30-1, a high-side diode 35-1, a low-side switching element 40-1, and a low-side diode 45-1.

[0111] The HVIC 60-1 corresponds to the HVICs 60a, 60b, and 60c, the LVIC 20-1 corresponds to the LVIC 20, and the bootstrap unit 50-1 corresponds to the bootstrap units 50a, 50b, and 50c.

[0112] Furthermore, the high-side switching element 30-1 corresponds to the high-side switching elements 30a, 30b, and 30c, and the high-side diode 35-1 corresponds to the high-side diodes 35a, 35b, and 35c. Furthermore, the low-side switching element 40-1 corresponds to the low-side switching elements 40a, 40b, and 40c, and the low-side diode 45-1 corresponds to the low-side diodes 45a, 45b, and 45c.

[0113] Here, the LVIC 20-1 (drive circuit) outputs a gate control signal (drive control signal) based on a drive signal transmitted from the control unit 110 to control the on / off switching of the low-side switching element 40-1.

[0114] The LVIC 20-1 also includes a drive control circuit 2a and an overvoltage protection circuit 10-1. The drive control circuit 2a includes Zener diodes ZD21 and ZD22, a resistor R20, a comparator 21, a reference voltage source ref20, a noise filter 22, a delay circuit 23, and a driver 24. The overvoltage protection circuit 10-1 is the overvoltage protection circuit 10a shown in FIG. 8 or the overvoltage protection circuit 10b shown in FIG. 9.

[0115] Low side power supply terminal V CCL is connected to the power supply terminal VCC and the cathode of the Zener diode ZD21 of the overvoltage protection circuit 10-1. The drive signal input terminals IN(LU), IN(LV), and IN(LW) are connected to the anode of the Zener diode ZD21, the cathode of the Zener diode ZD22, one end of the resistor R20, and the non-inverting input terminal (+) of the comparator 21.

[0116] The common ground terminal COM is connected to the ground terminal of the overvoltage protection circuit 10-1, the anode of the Zener diode ZD22, and then to GND. The other end of the resistor R20 is connected to GND. The positive electrode of the reference voltage source ref20 is connected to the inverting input terminal (-) of the comparator 21, and the negative electrode of the reference voltage source ref20 is connected to GND.

[0117] Here, when a drive signal output from the control unit 110 to turn on the low-side switching element 40-1 is input to any of the drive signal input terminals IN(LU), IN(LV), and IN(LW), the drive signal is input to the non-inverting input terminal (+) of the comparator 21.

[0118] Comparator 21 outputs an H-level signal when the voltage level of the input drive signal is higher than the reference voltage output from reference voltage source ref20. Noise filter 22 shapes the output signal from comparator 21 to remove noise. Delay circuit 23 delays the noise-removed H-level signal by a predetermined time. Driver 24 amplifies the H-level signal delayed by the predetermined time to the gate threshold voltage level of low-side switching element 40-1, and inputs the amplified gate control signal to the gate of low-side switching element 40-1 to turn on low-side switching element 40-1.

[0119] In addition, the low-side power supply terminal V CCL The Zener diodes ZD21 and ZD22 connected between the LVIC20-1 and the common ground terminal COM are built into the LVIC20-1 to protect it from surge voltage input.

[0120] A hysteresis comparator is used for the comparator 21. A hysteresis comparator is a circuit with a hysteresis setting to prevent the output level from switching frequently even when affected by short-term level fluctuations, and the use of a hysteresis comparator outputs a stable H-level (or L-level) signal.

[0121] On the other hand, the LVIC20-1 has an overvoltage protection circuit 10-1 connected to the low-side power supply terminal V CCL and the common ground terminal COM. CCL In addition, even if an overvoltage such as ESD occurs, the overvoltage protection circuit 10-1 provides stepwise overvoltage protection according to the magnitude of the overvoltage, preventing damage to circuit elements within the LVIC 20-1 while suppressing degradation of the overvoltage protection function, thereby achieving highly accurate and reliable overvoltage protection. Note that, although the overvoltage protection function is described as being provided in the LVIC in Fig. 11, it is not limited to this, and the HVIC may also have the overvoltage protection function.

[0122] Although the embodiments have been described above, the configuration of each part shown in the embodiments can be replaced with other parts having similar functions. Also, any other components or processes may be added. Furthermore, any two or more configurations (features) of the above-described embodiments may be combined. [Explanation of symbols]

[0123] 1 Overvoltage protection circuit 1a Overvoltage detection circuit 1b Resistor value selection circuit 1c clamp circuit 1c1 resistor 1c2 transistor VCC power supply pin Vin Voltage applied to the power supply terminal st1, st2, st3 overvoltage condition v1, v2, v3 resistance values Ib1, Ib2, Ib3 drive current Icr1, Icr2, Icr3 Current drawn from power terminals

Claims

1. an overvoltage detection circuit that detects whether or not the voltage applied to the power supply terminal is in an overvoltage state; a resistance value selection circuit that selects a predetermined resistance value from a plurality of resistance values ​​in accordance with the overvoltage state; a clamp circuit for clamping the voltage, the clamp circuit including: resistors having the plurality of resistance values; and a transistor that is turned on by a drive current that flows based on the selected predetermined resistance value to form a current path between the power supply terminal and a ground terminal and draw a current from the power supply terminal; With overvoltage protection circuit.

2. 2. The overvoltage protection circuit according to claim 1, wherein the overvoltage detection circuit detects a plurality of states of the overvoltage depending on the magnitude of the voltage, and the resistance value selection circuit increases the predetermined resistance value to be selected as the voltage increases.

3. 3. The overvoltage protection circuit of claim 2, wherein the overvoltage detection circuit detects a first overvoltage condition when the voltage is greater than or equal to a first voltage value and less than a second voltage value, and detects a second overvoltage condition when the voltage is greater than or equal to the second voltage value.

4. the resistor is made of a polyimide material, and the clamp circuit further includes a Zener diode connected in anti-series to a first end of the resistor; The resistance value selection circuit when the first overvoltage condition is detected, passing a current through a predetermined point located between the first end and a second end of the resistor connected to the base of the transistor to select a first resistance value formed between the predetermined point and the second end of the resistor; and when the second overvoltage condition is detected, passing a current through the first end to select a second resistance value formed between the first end and the second end of the resistor, the second resistance value being greater than the first resistance value.

4. The overvoltage protection circuit of claim 3.

5. The collector of the transistor is connected to the power supply terminal, and the emitter of the transistor is connected to the ground terminal; The transistor is When the first overvoltage state occurs, the Zener diode is turned on by a first drive current flowing through the resistor having the first resistance value due to the Zener diode being conductive, thereby forming the current path and drawing out a first current; When the second overvoltage state occurs, the Zener diode is turned on by a second drive current smaller than the first drive current, which flows through the resistor having the second resistance value, thereby forming the current path and drawing out a second current smaller in amount than the first current.

5. The overvoltage protection circuit of claim 4.

6. the overvoltage detection circuit includes a first comparator, a first voltage dividing resistor, a second voltage dividing resistor, a first reference voltage source, a second comparator, a third voltage dividing resistor, a fourth voltage dividing resistor, a second reference voltage source, a two-input, one-output logical product element, and an inverter element; the resistance value selection circuit includes a first resistance value selection circuit including a first transistor and a first base resistor, and a second resistance value selection circuit including a second transistor and a second base resistor; a first voltage obtained by dividing the voltage by the first voltage dividing resistor and the second voltage dividing resistor is input to a first non-inverting input terminal of the first comparator, and a first reference voltage output from the first reference voltage source is input to an inverting input terminal of the first comparator; a second voltage obtained by dividing the voltage by the third voltage dividing resistor and the fourth voltage dividing resistor is input to a non-inverting input terminal of the second comparator, and a second reference voltage output from the second reference voltage source is input to an inverting input terminal of the second comparator; a collector of the first transistor and a collector of the second transistor are connected to the power supply terminal; an output terminal of the first comparator is connected to one input terminal of the AND element, and an output terminal of the second comparator is connected to an input terminal of the inverter element and a base of the second transistor via the second base resistor; an output terminal of the inverter element is connected to the other input terminal of the AND element, and an output terminal of the AND element is connected to the base of the first transistor via the first base resistor; an emitter of the first transistor connected to the predetermined point of the resistor, an emitter of the second transistor connected to the first end of the resistor and a cathode of the Zener diode; the second end of the resistor is connected to the base of the transistor, the emitter of the transistor is connected to the anode of the Zener diode and the ground terminal, and a pull-down resistor is connected between the base of the transistor and the ground terminal.

6. The overvoltage protection circuit of claim 5.

7. the resistor includes a first resistor and a second resistor, and the clamp circuit further includes a Zener diode connected in anti-series to one end of the first resistor and one end of the second resistor; The resistance value selection circuit selecting a first resistance value for the first resistor when the first overvoltage condition is detected; selecting a second resistance value obtained by adding the first resistance value and the resistance value of the second resistor when the second overvoltage state is detected; 4. The overvoltage protection circuit of claim 3.

8. The collector of the transistor is connected to the power supply terminal, and the emitter of the transistor is connected to the ground terminal; The transistor is When the first overvoltage state occurs, the Zener diode is turned on by a first drive current flowing through the first resistor having the first resistance value, thereby forming the current path and drawing out a first current; When the Zener diode is in the second overvoltage state, the Zener diode is turned on by a second drive current smaller than the first drive current, which flows through a series combined resistance of the first resistor and the second resistor having the second resistance value, thereby forming the current path and drawing out a second current smaller in amount than the first current.

8. The overvoltage protection circuit of claim 7.

9. the overvoltage detection circuit includes a first comparator, a first voltage dividing resistor, a second voltage dividing resistor, a first reference voltage source, a second comparator, a third voltage dividing resistor, a fourth voltage dividing resistor, a second reference voltage source, a two-input, one-output logical product element, and an inverter element; the resistance value selection circuit includes a first resistance value selection circuit including a first transistor and a first base resistor, and a second resistance value selection circuit including a second transistor and a second base resistor; a first voltage obtained by dividing the voltage by the first voltage dividing resistor and the second voltage dividing resistor is input to a first non-inverting input terminal of the first comparator, and a first reference voltage output from the first reference voltage source is input to an inverting input terminal of the first comparator; a second voltage obtained by dividing the voltage by the third voltage dividing resistor and the fourth voltage dividing resistor is input to a non-inverting input terminal of the second comparator, and a second reference voltage output from the second reference voltage source is input to an inverting input terminal of the second comparator; a collector of the first transistor and a collector of the second transistor are connected to the power supply terminal; an output terminal of the first comparator is connected to one input terminal of the AND element, and an output terminal of the second comparator is connected to an input terminal of the inverter element and a base of the second transistor via the second base resistor; an output terminal of the inverter element is connected to the other input terminal of the AND element, and an output terminal of the AND element is connected to the base of the first transistor via the first base resistor; an emitter of the first transistor is connected to one end of the first resistor, one end of the second resistor and a cathode of the Zener diode, an emitter of the second transistor is connected to the other end of the second resistor, and the other end of the first resistor is connected to a base of the transistor; an emitter of the transistor is connected to the anode of the Zener diode and the ground terminal, and a pull-down resistor is connected between the base of the transistor and the ground terminal; 9. The overvoltage protection circuit of claim 8.

10. a switching element that switches on and off based on a drive control signal to operate a load; a drive control circuit that outputs the drive control signal based on a drive signal transmitted from a control unit, and a drive circuit including an overvoltage protection circuit; The overvoltage protection circuit an overvoltage detection circuit that detects whether or not the voltage applied to the power supply terminal of the drive circuit is in an overvoltage state; a resistance value selection circuit that selects a predetermined resistance value from a plurality of resistance values ​​in accordance with the overvoltage state; a clamp circuit that clamps the voltage, the clamp circuit including: resistors having the plurality of resistance values; and a transistor that is turned on by a drive current that flows based on the selected predetermined resistance value to form a current path between the power supply terminal and a ground terminal and draws a current from the power supply terminal. Semiconductor device.

11. 11. The semiconductor device according to claim 10, wherein said overvoltage detection circuit detects a plurality of states of said overvoltage depending on the magnitude of said voltage, and said resistance value selection circuit increases said predetermined resistance value to be selected as said voltage increases.

12. 12. The semiconductor device according to claim 11, wherein the overvoltage detection circuit detects a first overvoltage state in which the voltage is equal to or greater than a first voltage value and less than a second voltage value, and detects a second overvoltage state in which the voltage is equal to or greater than the second voltage value.

13. the resistor is made of a polyimide material, and the clamp circuit further includes a Zener diode connected in anti-series to a first end of the resistor; The resistance value selection circuit when the first overvoltage condition is detected, passing a current through a predetermined point located between the first end and a second end of the resistor connected to the base of the transistor to select a first resistance value formed between the predetermined point and the second end of the resistor; and when the second overvoltage condition is detected, passing a current through the first end to select a second resistance value formed between the first end and the second end of the resistor, the second resistance value being greater than the first resistance value.

13. The semiconductor device according to claim 12.

14. The collector of the transistor is connected to the power supply terminal, and the emitter of the transistor is connected to the ground terminal; The transistor is When the first overvoltage state occurs, the Zener diode is turned on by a first drive current flowing through the resistor having the first resistance value due to the Zener diode being conductive, thereby forming the current path and drawing out a first current; When the second overvoltage state occurs, the Zener diode is turned on by a second drive current smaller than the first drive current, which flows through the resistor having the second resistance value, thereby forming the current path and drawing out a second current smaller in amount than the first current.

14. The semiconductor device according to claim 13.

15. the overvoltage detection circuit includes a first comparator, a first voltage dividing resistor, a second voltage dividing resistor, a first reference voltage source, a second comparator, a third voltage dividing resistor, a fourth voltage dividing resistor, a second reference voltage source, a two-input, one-output logical product element, and an inverter element; the resistance value selection circuit includes a first resistance value selection circuit including a first transistor and a first base resistor, and a second resistance value selection circuit including a second transistor and a second base resistor; a first voltage obtained by dividing the voltage by the first voltage dividing resistor and the second voltage dividing resistor is input to a first non-inverting input terminal of the first comparator, and a first reference voltage output from the first reference voltage source is input to an inverting input terminal of the first comparator; a second voltage obtained by dividing the voltage by the third voltage dividing resistor and the fourth voltage dividing resistor is input to a non-inverting input terminal of the second comparator, and a second reference voltage output from the second reference voltage source is input to an inverting input terminal of the second comparator; a collector of the first transistor and a collector of the second transistor are connected to the power supply terminal; an output terminal of the first comparator is connected to one input terminal of the AND element, and an output terminal of the second comparator is connected to an input terminal of the inverter element and a base of the second transistor via the second base resistor; an output terminal of the inverter element is connected to the other input terminal of the AND element, and an output terminal of the AND element is connected to the base of the first transistor via the first base resistor; an emitter of the first transistor connected to the predetermined point of the resistor, an emitter of the second transistor connected to the first end of the resistor and a cathode of the Zener diode; the second end of the resistor is connected to the base of the transistor, the emitter of the transistor is connected to the anode of the Zener diode and the ground terminal, and a pull-down resistor is connected between the base of the transistor and the ground terminal.

15. The semiconductor device according to claim 14.

16. the resistor includes a first resistor and a second resistor, and the clamp circuit further includes a Zener diode connected in anti-series to one end of the first resistor and one end of the second resistor; The resistance value selection circuit selecting a first resistance value for the first resistor when the first overvoltage condition is detected; selecting a second resistance value obtained by adding the first resistance value and the resistance value of the second resistor when the second overvoltage state is detected; 13. The semiconductor device according to claim 12.

17. The collector of the transistor is connected to the power supply terminal, and the emitter of the transistor is connected to the ground terminal; The transistor is When the first overvoltage state occurs, the Zener diode is turned on by a first drive current flowing through the first resistor having the first resistance value, thereby forming the current path and drawing out a first current; When the Zener diode is in the second overvoltage state, the Zener diode is turned on by a second drive current smaller than the first drive current, which flows through a series combined resistance of the first resistor and the second resistor having the second resistance value, thereby forming the current path and drawing out a second current smaller in amount than the first current.

17. The semiconductor device according to claim 16.

18. the overvoltage detection circuit includes a first comparator, a first voltage dividing resistor, a second voltage dividing resistor, a first reference voltage source, a second comparator, a third voltage dividing resistor, a fourth voltage dividing resistor, a second reference voltage source, a two-input, one-output logical product element, and an inverter element; the resistance value selection circuit includes a first resistance value selection circuit including a first transistor and a first base resistor, and a second resistance value selection circuit including a second transistor and a second base resistor; a first voltage obtained by dividing the voltage by the first voltage dividing resistor and the second voltage dividing resistor is input to a first non-inverting input terminal of the first comparator, and a first reference voltage output from the first reference voltage source is input to an inverting input terminal of the first comparator; a second voltage obtained by dividing the voltage by the third voltage dividing resistor and the fourth voltage dividing resistor is input to a non-inverting input terminal of the second comparator, and a second reference voltage output from the second reference voltage source is input to an inverting input terminal of the second comparator; a collector of the first transistor and a collector of the second transistor are connected to the power supply terminal; an output terminal of the first comparator is connected to one input terminal of the AND element, and an output terminal of the second comparator is connected to an input terminal of the inverter element and a base of the second transistor via the second base resistor; an output terminal of the inverter element is connected to the other input terminal of the AND element, and an output terminal of the AND element is connected to the base of the first transistor via the first base resistor; an emitter of the first transistor is connected to one end of the first resistor, one end of the second resistor and a cathode of the Zener diode, an emitter of the second transistor is connected to the other end of the second resistor, and the other end of the first resistor is connected to a base of the transistor; an emitter of the transistor is connected to the anode of the Zener diode and the ground terminal, and a pull-down resistor is connected between the base of the transistor and the ground terminal; 18. The semiconductor device according to claim 17.

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