WO2024084646A1

WO2024084646A1 - Overcurrent protection circuit and semiconductor device

Info

Publication number: WO2024084646A1
Application number: PCT/JP2022/039065
Authority: WO
Inventors: 良太川島
Original assignee: サンケン電気株式会社
Priority date: 2022-10-20
Filing date: 2022-10-20
Publication date: 2024-04-25

Abstract

Provided is an overcurrent protection circuit which is highly versatile and compatible with various switching elements.　An overcurrent protection circuit 10 detects an overcurrent when an OCP interruption time T_OCP has elapsed in a state of an OCP voltage value V_OCP being more than an OCP threshold value Vref. The overcurrent protection circuit comprises: a plurality of comparators CMP11, CMP12, CMP13 which compare the OCP voltage value V_OCP with a plurality of different OCP threshold values Vref11, Vref12, Vref13; and a plurality of interruption time generation circuits [(switch element Q11, resistor R11, and capacitor C11), (switch element Q12, resistor R12, and capacitor C12), (switch element Q13, resistor R13, and capacitor C13)] that generate different OCP interruption times T_OCP11, T_OCP12, T_OCP13, for the respective comparators CMP11, CMP12, CMP13.

Description

Overcurrent protection circuit, semiconductor device

The present invention relates to an overcurrent protection circuit that prevents an overcurrent from flowing through a power supply or load.

A semiconductor device that integrates a motor driver that drives a motor is known. The motor driver converts drive commands from a controller into drive signals with optimal voltage and switching speed to drive a built-in inverter circuit and output a drive voltage that drives the motor. The motor driver is provided with an overcurrent protection (OCP: Over Current Protection) circuit that detects overcurrent, such as a motor overload, and stops the switching operation to prevent overcurrent from flowing to the power supply or load (see, for example, Patent Document 1).

JP 2020-188610 A

General overcurrent protection operation involves comparing the current IC flowing through a switching element with the OCP threshold, and judging whether or not an overcurrent is flowing based on the comparison result. Depending on the OCP threshold, the recovery current that can occur during normal operation of the switching element enclosed by the dotted line as shown in Figure 10(a) may become larger, causing a malfunction (turning off). This malfunction can be prevented by extending the OCP cut-off time, during which no overcurrent judgment is made. Therefore, if the OCP threshold needs to be reduced due to the type or combination of switching elements, it is effective to extend the OCP cut-off time to prevent malfunction.

However, if the OCP shutdown time is lengthened, as shown by the solid line in Figure 10(b), if the overcurrent during abnormal operation is large, the switching element will suffer thermal destruction in a short time. As a countermeasure, if the OCP shutdown time is shortened, the switching operation can be stopped before thermal destruction occurs. Therefore, shortening the OCP shutdown time is an effective way to prevent thermal destruction.

The appropriate OCP threshold and OCP cut-off time vary depending on the type, generation, size, and combination of switching elements. Therefore, every time a new motor driver was developed, it was necessary to develop a new overcurrent protection circuit with the OCP threshold and OCP cut-off time set to appropriate values. This resulted in a huge number of overcurrent protection circuit varieties that were difficult to manage, and also required a long development period and labor. Furthermore, the number of assembly prototypes increased, which could lead to installation errors.

The present invention was made in consideration of these problems, and its purpose is to provide a versatile overcurrent protection circuit that can be used with a variety of switching elements.

In order to achieve the above object, the overcurrent protection circuit according to the present invention is configured as follows.
The overcurrent protection circuit of the present invention is an overcurrent protection circuit that uses a current detection element to detect the current flowing through a switching element as an OCP voltage value, compares the OCP voltage value with an OCP threshold value, and detects an overcurrent when an OCP cut-off time has elapsed with the OCP voltage value exceeding the OCP threshold value, and is characterized in that it comprises a plurality of comparators that compare the OCP voltage value with a plurality of different OCP threshold values, respectively, and a plurality of cut-off time generation circuits that generate a different OCP cut-off time for each of the plurality of comparators, and the cut-off time generation circuit generates a shorter OCP cut-off time the higher the OCP threshold value of the comparator is.
Moreover, an overcurrent protection circuit according to the present invention is an overcurrent protection circuit that detects a current flowing through a switching element as an OCP voltage value using a current detection element, compares the OCP voltage value with an OCP threshold value, and detects an overcurrent when an OCP cut-off time has elapsed with the OCP voltage value exceeding the OCP threshold value, the overcurrent protection circuit comprising: a first overcurrent protection circuit; and a second overcurrent protection circuit, the first overcurrent protection circuit comprising a plurality of first comparators that compare the OCP voltage value with a plurality of different OCP threshold values, respectively, and a plurality of first cut-off time generation circuits that generate different OCP cut-off times for each of the first comparators, the first cut-off time generation circuit generating a shorter OCP cut-off time as the OCP threshold value of the first comparator is higher, and receives an input of a main power supply voltage value obtained by dividing a main power supply voltage, and the OCP threshold value is set to a lower voltage as the main power supply voltage is higher and accepts an input of a temperature detected by a temperature sensor, the OCP threshold is set to a lower voltage as the temperature is higher, the second overcurrent protection circuit comprises a plurality of second comparators which compare the OCP voltage value with a plurality of different OCP thresholds, and a plurality of second cut-off time generation circuits which generate different OCP cut-off times for each of the plurality of second comparators, the second cut-off time generation circuit generating a shorter OCP cut-off time as the OCP threshold of the second comparator is higher, accepts an input of a user setting value, and the OCP threshold is changeable based on the user setting value, and the first overcurrent protection circuit and the second overcurrent protection circuit detect an overcurrent using either one selected based on the user setting value.

The overcurrent protection circuit of the present invention detects overcurrent with multiple OCP cutoff times that are appropriately set according to multiple OCP thresholds, and can detect how susceptible a state is to thermal destruction and appropriately control the OCP cutoff time, thereby achieving the effect of being able to accommodate a variety of switching elements that have different times until thermal destruction in the event of an abnormality.

1 is a diagram showing an example of the configuration of a motor driver incorporating an overcurrent protection circuit according to the present invention; 1 is a diagram showing a configuration example of an embodiment of an overcurrent protection circuit according to the present invention; 3 is a diagram showing an example of the configuration of a variable voltage source used in the first overcurrent protection circuit shown in FIG. 2 . 3 is a diagram illustrating an example of the operation of the first overcurrent protection circuit illustrated in FIG. 2 . 3 is a diagram showing an example of the configuration of a variable voltage source used in the second overcurrent protection circuit shown in FIG. 2 . 3 is a diagram illustrating an example of the operation of the second overcurrent protection circuit illustrated in FIG. 2 . 3 is a diagram showing a modification of the second overcurrent protection circuit shown in FIG. 2 . FIG. 8 is a diagram illustrating a configuration example of a select circuit illustrated in FIG. 7 . 9 is a truth table of the select circuit shown in FIG. 8 . FIG. 1 is a diagram illustrating a conventional overcurrent protection operation.

Below, a preferred embodiment of the present invention will be described with reference to the attached drawings.

The motor driver of this embodiment is a motor driving device that drives a motor 1, and referring to FIG. 1, it includes an inverter circuit 2, a high-side driver IC3 and a low-side driver IC4 that are driving circuits, and a controller 5 that is a control circuit.

The inverter circuit 2 includes a half-bridge circuit for the U phase, a half-bridge circuit for the V phase, and a half-bridge circuit for the W phase. Each half-bridge circuit includes a high-side switching element QH and a low-side switching element QL connected in series between the motor power supply voltage Vpp and the common line. Capacitor C1 is an input capacitor connected between the motor power supply voltage Vpp and the common line. The high-side switching element QH and the low-side switching element QL are configured, for example, as insulated gate bipolar transistors (IGBTs).

The high-side driver IC3 and the low-side driver IC4 are semiconductor devices formed by sealing a semiconductor integrated circuit in a package made of resin. The high-side driver IC3 and the low-side driver IC4 may be in the same package, and may have the inverter circuit 2 built in.

The high-side driver IC3 has a control power input terminal Vcc1 that inputs the control power voltage Vcc, and a control ground terminal COM1 that is connected to the common line. Capacitor C2 is an input capacitor connected between the control power voltage Vcc and the common line. The high-side driver IC3 has floating power terminals VB1-3 and floating power terminals HS1-3. Capacitors C3-C5 are capacitors connected between VB1-3 and HS1-3.

The high-side driver IC3 has high-side control signal input terminals HIN1-3 and high-side drive signal output terminals HO1-3. Based on the high-side control signal from the controller 5 input to the high-side control signal input terminals HIN1-3, the high-side driver IC3 generates a high-side drive signal that drives the high-side switching element QH of the inverter circuit 2 on and off, and outputs it from the high-side drive signal output terminals HO1-3.

The high-side driver IC3 has an error signal input terminal SD. When an error signal is input from the error signal input terminal SD, the high-side driver IC3 stops the on/off driving of the high-side switching element QH and switches the high-side switching element QH to a cut-off (off) state.

The low-side driver IC4 has a control power supply input terminal Vcc2 that inputs the control power supply voltage Vcc, and a control ground terminal COM2 that is connected to the common line.

The low-side driver IC4 has low-side control signal input terminals LIN1-3 and low-side drive signal output terminals LO1-3. Based on the low-side control signal from the controller 5 input to the low-side control signal input terminals LIN1-3, the low-side driver IC4 generates a low-side drive signal that drives the low-side switching element QL of the inverter circuit 2 on and off, and outputs it from the low-side drive signal output terminals LO1-3.

The low-side driver IC4 has a motor power supply voltage detection terminal OVM, an overcurrent protection signal input terminal OCP, a user-defined terminal BTMS, and a temperature detection terminal VT.

The motor power supply voltage detection terminal OVM is connected between resistor R1 and variable resistor R2, which are connected in series between the motor power supply voltage Vpp and the common line, and the value obtained by dividing the motor power supply voltage Vpp by resistor R1 and variable resistor R2 is input as the power supply voltage value V _OVM . The variable resistor R2 is provided so that the user can adjust the detection level of the power supply voltage value V _OVM .

The overcurrent protection signal input terminal OCP is connected to the emitter of the low-side switching element QL connected to the common line via the current detection element Rs, and detects the current flowing from the low-side switching element QL and inputs it as an OCP voltage value _{V_OCP} .

A variable voltage source VA is connected to the user setting terminal BTMS, and the voltage of the variable voltage source VA is input as a user setting value V _BTMS .

The temperature detection terminal VT is connected to a temperature sensor 6, and the temperature detected by the temperature sensor 6 is input as a temperature voltage value _VVT .

The error signal output terminal FO is connected to the error signal input terminal SD of the high-side driver IC3 and the controller 5, and the error signal output from the error signal output terminal FO is input to the error signal input terminal SD of the high-side driver IC3 and the controller 5.

The low-side driver IC4 includes an overcurrent protection circuit 10 as shown in Fig. 2. The overcurrent protection circuit 10 is a circuit that detects an overcurrent based on an OCP voltage value _{V_OCP} input from an overcurrent protection signal input terminal OCP and outputs an error signal, and includes a first overcurrent protection circuit 11 and a second overcurrent protection circuit 21. The overcurrent protection circuit 10 detects an overcurrent using either the first overcurrent protection circuit 11 or the second overcurrent protection circuit 21.

Either the first overcurrent protection circuit 11 or the second overcurrent protection circuit 21 is selected by a user setting value _VBTMS input to a user setting terminal BTMS. The user setting value _VBTMS is input to one input terminal of an AND circuit AND11 provided at the output stage of the first overcurrent protection circuit 11, and is also input via an inverter INV20 to one input terminal of an AND circuit AND21 provided at the output stage of the second overcurrent protection circuit 21.

When the user set value _VBTMS is a voltage at which the input judgment of the AND circuit AND11 and the inverter INV20 is at a high level (e.g., 3 V or more), the AND circuit AND11 is turned on and the AND circuit AND21 is turned off, selecting the first overcurrent protection circuit 11. When the user set value _VBTMS is a voltage at which the input judgment of the AND circuit AND11 and the inverter INV20 is at a low level (e.g., less than 3 V), the AND circuit AND11 is turned off and the AND circuit AND21 is turned on, selecting the second overcurrent protection circuit 21.

The first overcurrent protection circuit 11 includes comparators CMP11, CMP12, and CMP13 whose non-inverting input terminals are connected to the overcurrent protection signal input terminal OCP and whose inverting input terminals are connected to

variable voltage sources

111, 112, and 113, respectively. The comparator CMP11 outputs a high level when the OCP voltage value _{V_OCP} exceeds an OCP threshold Vref11 generated by the variable voltage source 111. The comparator CMP12 outputs a high level when the OCP voltage value _{V_OCP} exceeds an OCP threshold Vref12 generated by the variable voltage source 112. The comparator CMP13 outputs a high level when the OCP voltage value _{V_OCP} exceeds an OCP threshold Vref13 generated by the variable voltage source 113.

The OCP threshold Vref11 is set lower than the OCP threshold Vref12, which is set lower than the OCP threshold Vref13 (Vref11<Vref12<Vref13). That is, the comparators CMP11, CMP12, and CMP13 compare the OCP voltage value _VOCP with the OCP thresholds Vref11, Vref12, and Vref13, which have different potentials, respectively.

A series circuit consisting of a resistor R11 and a switch element Q11 is connected between the internal voltage Reg and the common line, and a capacitor C11 is connected in parallel to the switch element Q11. The output terminal of the comparator CMP11 is connected to the control terminal of the switch element Q11 via an inverter INV11. Therefore, when the OCP voltage value _VOCP exceeds the OCP threshold value Vref11, the comparator CMP11 outputs a high level (the inverter INV11 outputs a low level), and the switch element Q11 transitions to the off state. When the switch element Q11 transitions to the off state, charging of the capacitor C11 begins, and when the voltage of the capacitor C11 reaches a high level due to charging, an error signal (high level) is output.

The time it takes for the voltage of capacitor C11 to reach a high level through charging is the OCP cut-off time _TOCP11 that masks the detection of an overcurrent. That is, the switch element Q11, resistor R11, and capacitor C11 function as a cut-off time generating circuit that generates the OCP cut-off time _TOCP11 . If the OCP voltage value _VOCP becomes equal to or lower than the OCP threshold value Vref11 before the OCP cut-off time _TOCP11 has elapsed, the switch element Q11 transitions to the ON state, the voltage of capacitor C11 is discharged, and an error signal (high level) is not output.

A series circuit consisting of a resistor R12 and a switch element Q12 is connected between the internal voltage Reg and the common line, and a capacitor C12 is connected in parallel to the switch element Q12. The output terminal of the comparator CMP12 is connected to the control terminal of the switch element Q12 via an inverter INV12. Therefore, when the OCP voltage value V _OCP exceeds the OCP threshold value Vref12, the comparator CMP12 outputs a high level (the inverter INV12 outputs a low level), and the switch element Q12 transitions to the off state. When the switch element Q12 transitions to the off state, charging of the capacitor C12 begins, and when the voltage of the capacitor C12 reaches a high level due to charging, an error signal (high level) is output.

The time required for the voltage of the capacitor C12 to reach a high level by charging is the OCP cutoff time T _OCP12 that masks the detection of an overcurrent. That is, the switch element Q12, the resistor R12, and the capacitor C12 function as a cutoff time generating circuit that generates the OCP cutoff time T _OCP12 . The OCP cutoff time T _OCP12 is set to a time shorter than the OCP cutoff time T _OCP11 (T _OCP12 <T _OCP11 ). The time constant of the resistor R12 and the capacitor C12 is set to a value smaller than the time constant of the resistor R11 and the capacitor C11. Therefore, when the OCP voltage value V _OCP exceeds the OCP threshold value Vref12, it also exceeds the OCP threshold value Vref11 and charging of the capacitor C11 is started, but if the voltage of the capacitor C12 reaches a high level by charging before the OCP cutoff time T _OCP11 has elapsed, an error signal (high level) is output. If the OCP voltage value _{V_OCP} becomes equal to or lower than the OCP threshold value Vref12 before the OCP cutoff time _{T_OCP12} has elapsed, the switch element Q12 transitions to the on state, the voltage of the capacitor C12 is discharged, and no error signal (high level) is output.

A series circuit consisting of a resistor R13 and a switch element Q13 is connected between the internal voltage Reg and the common line, and a capacitor C13 is connected in parallel to the switch element Q13. The output terminal of the comparator CMP13 is connected to the control terminal of the switch element Q13 via an inverter INV13. Therefore, when the OCP voltage value V _OCP exceeds the OCP threshold value Vref13, the comparator CMP13 outputs a high level (the inverter INV13 outputs a low level), and the switch element Q13 transitions to the off state. When the switch element Q13 transitions to the off state, charging of the capacitor C13 begins, and when the voltage of the capacitor C13 reaches a high level due to charging, an error signal (high level) is output.

The time required for the voltage of the capacitor C13 to reach a high level by charging is the OCP cut-off time T _OCP13 that masks the detection of an overcurrent. That is, the switch element Q13, the resistor R13, and the capacitor C13 function as a cut-off time generating circuit that generates the OCP cut-off time T _OCP13 . The OCP cut-off time T _OCP13 is set to a time shorter than the OCP cut-off time T _OCP13 (T _OCP13 <T _OCP12 ). The time constant of the resistor R13 and the capacitor C13 is set to a value smaller than the time constant of the resistor R12 and the capacitor C12. Therefore, when the OCP voltage value V _OCP exceeds the OCP threshold value Vref13, it also exceeds the OCP threshold value Vref12 and charging of the capacitor C12 is started, but if the voltage of the capacitor C13 reaches a high level by charging before the OCP cut-off time T _OCP12 has elapsed, an error signal (high level) is output. If the OCP voltage value _{V_OCP} becomes equal to or lower than the OCP threshold value Vref13 before the OCP shutoff time _{T_OCP13} has elapsed, the switch element Q13 transitions to the on state, the voltage of the capacitor C13 is discharged, and no error signal (high level) is output.

The voltages of the capacitors C11 to C13 are input to the first to third input terminals of the OR circuit OR11, respectively. The output terminal of the OR circuit OR11 is connected to the other input terminal of the AND circuit AND11, and when the voltage of V _TMMS input to the AND circuit AND11 is in a high level state, an error signal is output from the overcurrent protection circuit 10 when the voltage of any of the capacitors C11 to C13 reaches a high level. The error signal from the overcurrent protection circuit 10 is input to a control unit 20 built into the low-side driver IC4 and is output from an error signal output terminal FO. When the error signal is input from the overcurrent protection circuit 10, the control unit 20 stops the on/off driving of the low-side switching element QL and switches the low-side switching element QL to a cut-off (off) state.

The variable voltage source 111 sets the OCP threshold value Vref11 based on the power supply voltage value V _OVM input from the motor power supply voltage detection terminal OVM and the temperature voltage value V VT input from the temperature detection terminal _VT . Referring to Fig. 3, the variable voltage source 111 has a series circuit made up of resistors R30 and R40 connected between the internal voltage Reg and the common line, and outputs the voltage at the connection point between the resistors R30 and R40 as the OCP threshold value Vref11.

Connected in parallel to resistor R40 are a series circuit consisting of resistor R31 and switch element Q31, a series circuit consisting of resistor R32 and switch element Q32, a series circuit consisting of resistor R33 and switch element Q33, a series circuit consisting of resistor R41 and switch element Q41, a series circuit consisting of resistor R42 and switch element Q42, and a series circuit consisting of resistor R43 and switch element Q43. Therefore, the voltage of the OCP threshold Vref11 changes depending on the state of switch elements Q31, Q32, Q33, Q41, Q42, and Q43.

The switch elements Q31, Q32, and Q33 are each composed of, for example, a MOS transistor. The control terminal of the switch element Q31 is connected to the output terminal of a comparator CMP31 that compares the power supply voltage value _{V_OVM} with a reference voltage Vref31, and the switch element Q31 is turned on when the power supply voltage value _{V_OVM} exceeds the reference voltage Vref31. The control terminal of the switch element Q32 is connected to the output terminal of a comparator CMP32 that compares the power supply voltage value _{V_OVM} with a reference voltage Vref32 (Vref31<Vref32) that is higher than the reference voltage Vref31, and the switch element Q32 is turned on when the power supply voltage value _{V_OVM} exceeds the reference voltage Vref32. The control terminal of the switch element Q33 is connected to the output terminal of a comparator CMP33 that compares the power supply voltage value _{V_OVM} with a reference voltage Vref33 (Vref32<Vref33) that is higher than the reference voltage Vref32, and is turned on when the power supply voltage value _{V_OVM} exceeds the reference voltage Vref33. Therefore, when the power supply voltage value _{V_OVM} is equal to or lower than the reference voltage Vref31, all of the switch elements Q31, Q32, and Q33 are in the off state, when the power supply voltage value _{V_OVM} exceeds the reference voltage Vref31 and is equal to or lower than the reference voltage Vref32, only the switch element Q31 is in the on state, when the power supply voltage value _{V_OVM} exceeds the reference voltage Vref32 and is equal to or lower than the reference voltage Vref33, the switch elements Q31 and Q32 are in the on state, and when the power supply voltage value _{V_OVM} exceeds the reference voltage Vref33, all of the switch elements Q31, Q32, and Q33 are in the on state. As a result, the OCP threshold Vref11 is set to a lower voltage as the power supply voltage value V _OVM (motor power supply voltage Vpp) is higher.

The switching elements Q41, Q42, and Q43 are each composed of, for example, a MOS transistor. The control terminal of the switching element Q41 is connected via an inverter INV41 to an output terminal of a comparator CMP41 that compares the temperature voltage value _VVT with a reference voltage Vref41, and the switching element Q41 is turned off when the temperature voltage value _VVT exceeds the reference voltage Vref41. The control terminal of the switching element Q42 is connected via an inverter INV42 to an output terminal of a comparator CMP42 that compares the temperature voltage value _VVT with a reference voltage Vref42 (Vref41<Vref42) that is higher than the reference voltage Vref41, and the switching element Q42 is turned off when the temperature voltage value _VVT exceeds the reference voltage Vref42. The control terminal of the switch element Q43 is connected via an inverter INV43 to the output terminal of a comparator CMP43 that compares the temperature voltage value _VVT with a reference voltage Vref43 (Vref42<Vref43) higher than the reference voltage Vref42, and is turned off when the temperature voltage value _VVT exceeds the reference voltage Vref43. Therefore, when the temperature voltage value _VVT is equal to or lower than the reference voltage Vref41, all of the switch elements Q41, Q42, and Q43 are in the on state, when the temperature voltage value _VVT exceeds the reference voltage Vref41 and is equal to or lower than the reference voltage Vref42, only the switch element Q41 is in the off state, when the temperature voltage value _VVT exceeds the reference voltage Vref42 and is equal to or lower than the reference voltage Vref43, the switch elements Q41 and Q42 are in the off state, and when the temperature voltage value _VVT exceeds the reference voltage Vref43, all of the switch elements are in the off state. As a result, the OCP threshold Vref11 is set to a lower voltage as the temperature voltage value _VVT is lower (the temperature detected by the temperature sensor 6 is higher).

3, the OCP threshold Vref11 can be changed in 4×4=16 ways by combining the power supply voltage value V _OVM and the temperature voltage value V _VT . The number of voltages to which the OCP threshold Vref11 can be changed can be set appropriately.

Variable voltage sources

112 and 113 have a similar configuration to variable voltage source 111, and set OCP thresholds Vref12 and Vref13, respectively, based on the power supply voltage value _{V_OVM} and the temperature voltage value _{V_VT} . However, when the power supply voltage value _{V_OVM} and the temperature voltage value _{V_VT} are the same combination, the resistance values of

variable voltage sources

111, 112, and 113 are set so that the above-mentioned relationship (Vref11<Vref12<Vref13) is maintained.

4A, the OCP thresholds Vref11, Vref12, and Vref13, which are set by a combination of the power supply voltage value V _OVM when the motor power supply voltage Vpp=300 V and the temperature voltage value V _VT when the detection temperature is 50° C., are 1.0 V, 1.8 V, and 2.6 V, respectively. In this case, when the OCP voltage value V _OCP =0.9 V (18 A with the current detection element Rs=50 mΩ), V _OCP ≦Vref11, so the first overcurrent protection circuit 11 does not perform the OCP operation. At an OCP voltage value V _OCP =1.65V (33A with current detection element Rs=50mΩ), Vref11<V _OCP ≦Vref12, so the first overcurrent protection circuit 11 outputs an error signal when the OCP cut-off time T _OCP11 (e.g., 2μs) has elapsed in a state where Vref11<V _OCP . At an OCP voltage value V _OCP =2.3V (46A with current detection element Rs=50mΩ), Vref12<V _OCP ≦Vref13, so the first overcurrent protection circuit 11 outputs an error signal when the OCP cut-off time T _OCP12 (e.g., 1μs) has elapsed in a state where Vref12<V _OCP . In addition, since the OCP voltage value V _OCP = 2.3 V also satisfies Vref11 < V _OCP , the first overcurrent protection circuit 11 outputs an error signal even after the OCP cutoff time T _OCP11 (e.g., 2 μs) has elapsed in a state where Vref11 < V _OCP. However, since the error signal after T _OCP12 has already elapsed has already been input to the control unit 20, the low-side switching element QL is already in the off state.

4B, the OCP thresholds Vref11, Vref12, and Vref13, which are set by combining the power supply voltage value V _OVM when the motor power supply voltage Vpp=900 V and the temperature voltage value V _VT when the detected temperature is 50° C., are 0.8 V, 1.6 V, and 2.4 V, respectively. In this case, when the OCP voltage value V _OCP =0.9 V, Vref11<V _OCP ≦Vref12, so the first overcurrent protection circuit 11 outputs an error signal when the OCP cutoff time T _OCP11 (e.g., 2 μs) has elapsed in a state where Vref11<V _OCP . At OCP voltage values V _OCP =1.65 V and 2.3 V, Vref12<V _OCP ≦Vref13, so the first overcurrent protection circuit 11 outputs an error signal when the OCP cutoff time T _OCP12 (e.g., 1 μs) has elapsed in a state where Vref12<V _OCP . Note that at OCP voltage values V _OCP =1.65 V and 2.3 V, Vref11<V _OCP , so the first overcurrent protection circuit 11 outputs an error signal even after the OCP cutoff time T _OCP11 (e.g., 2 μs) has elapsed in a state where Vref11<V _OCP . However, since the error signal after the elapse of T _OCP12 has already been input to the control unit 20, the low-side switching element QL is already in the off state.

4(c), the OCP thresholds Vref11, Vref12, and Vref13, which are set by combining the power supply voltage value V _OVM when the motor power supply voltage Vpp=900 V and the temperature voltage value V _VT when the detected temperature is 100° C., are 0.6 V, 1.4 V, and 2.2 V, respectively. In this case, when the OCP voltage value V _OCP =0.9 V, Vref11<V _OCP ≦Vref12, so the first overcurrent protection circuit 11 outputs an error signal when the OCP cutoff time T _OCP11 (e.g., 2 μs) has elapsed in a state where Vref11<V _OCP . At an OCP voltage value V _OCP =1.65V, Vref12<V _OCP ≦Vref13, so the first overcurrent protection circuit 11 outputs an error signal when the OCP cutoff time T _OCP12 (e.g., 1 μs) has elapsed in a state where Vref12<V _OCP . Note that at an OCP voltage value V _OCP =1.65V, Vref11<V _OCP , so the first overcurrent protection circuit 11 outputs an error signal even if the OCP cutoff time T _OCP11 (e.g., 2 μs) has elapsed in a state where Vref11<V _OCP , but the error signal after the elapse of T _OCP12 has already been input to the control unit 20, so the low-side switching element QL is already in the off state. At an OCP voltage value V _OCP =2.3 V, Vref13<V _OCP , so the first overcurrent protection circuit 11 outputs an error signal when the OCP cutoff time T _OCP13 (e.g., 0.3 μs) has elapsed in a state where Vref13<V _OCP . Note that at an OCP voltage value V _OCP =2.3 V, Vref11<V _OCP , so the first overcurrent protection circuit 11 outputs an error signal even if the OCP cutoff time T _OCP11 (e.g., 2 μs) has elapsed in a state where Vref11<V _OCP , but the error signal after the elapse of T _OCP13 has already been input to the control unit 20, so the low-side switching element QL is already in the off state. Similarly, when the OCP voltage value V _OCP = 2.3 V, Vref12 < V _OCP , so the first overcurrent protection circuit 11 outputs an error signal even after the OCP cutoff time T _OCP12 (e.g., 1 μs) has elapsed in a state where Vref12 < V _OCP. However, since the error signal after T _OCP13 has already been input to the control unit 20, the low-side switching element QL is already in the off state.

With the above configuration, the first overcurrent protection circuit 11 changes the levels of the OCP thresholds Vref11, Vref12, and Vref13 to be compared with the OCP voltage value _VOCP depending on the power supply voltage value _VOVM and the temperature voltage value _VVT . The OCP thresholds Vref11, Vref12, and Vref13 are set to lower voltages as the power supply voltage value _VOVM (motor power supply voltage Vpp) is higher, and are set to lower voltages as the temperature voltage value _VVT is lower (the temperature detected by the temperature sensor 6 is higher). Different OCP cutoff times _TOCP11 , TOCP12, and TOCP13 are set for the OCP thresholds Vref11, _Vref12 , and _Vref13 , respectively. The OCP thresholds Vref11, Vref12, and Vref13 are set such that Vref11<Vref12<Vref13, and the OCP cutoff times T _OCP11 , T _OCP12 , and T _OCP13 are set such that T _OCP11 > T _OCP12 > T _OCP13 .

The second overcurrent protection circuit 21 includes comparators CMP21, CMP22, and CMP23 whose non-inverting input terminals are connected to the overcurrent protection signal input terminal OCP and whose inverting input terminals are connected to

variable voltage sources

211, 212, and 213, respectively. The comparator CMP21 outputs a high level when the OCP voltage value _{V_OCP} exceeds an OCP threshold Vref21 generated by the variable voltage source 211. The comparator CMP22 outputs a high level when the OCP voltage value _{V_OCP} exceeds an OCP threshold Vref22 generated by the variable voltage source 212. The comparator CMP23 outputs a high level when the OCP voltage value _{V_OCP} exceeds an OCP threshold Vref23 generated by the variable voltage source 213.

The OCP threshold Vref21 is set lower than the OCP threshold Vref22, which is set lower than the OCP threshold Vref23 (Vref21<Vref22<Vref23). That is, the comparators CMP21, CMP22, and CMP23 compare the OCP voltage value _VOCP with the OCP thresholds Vref21, Vref22, and Vref23, which have different potentials, respectively.

A series circuit consisting of a resistor R21 and a switch element Q21 is connected between the internal voltage Reg and the common line, and a capacitor C21 is connected in parallel to the switch element Q21. The output terminal of the comparator CMP21 is connected to the control terminal of the switch element Q21 via an inverter INV21. Therefore, when the OCP voltage value _VOCP exceeds the OCP threshold value Vref21, the comparator CMP21 outputs a high level (the inverter INV21 outputs a low level), and the switch element Q21 transitions to the off state. When the switch element Q21 transitions to the off state, charging of the capacitor C21 begins, and when the voltage of the capacitor C21 reaches a high level due to charging, an error signal (high level) is output.

The time it takes for the voltage of capacitor C21 to reach a high level through charging becomes the OCP cut-off time T _OCP21 that masks the detection of an overcurrent. That is, switch element Q21, resistor R21, and capacitor C21 function as a cut-off time generating circuit that generates the OCP cut-off time T _OCP21 . If the OCP voltage value V _OCP becomes equal to or lower than the OCP threshold value Vref21 before the OCP cut-off time T _OCP21 has elapsed, switch element Q21 transitions to the on state to discharge the voltage of capacitor C21, and an error signal (high level) is not output.

A series circuit consisting of a resistor R22 and a switch element Q22 is connected between the internal voltage Reg and the common line, and a capacitor C22 is connected in parallel to the switch element Q22. The output terminal of the comparator CMP22 is connected to the control terminal of the switch element Q22 via an inverter INV22. Therefore, when the OCP voltage value V _OCP exceeds the OCP threshold value Vref22, the comparator CMP22 outputs a high level (the inverter INV22 outputs a low level), and the switch element Q22 transitions to the off state. When the switch element Q22 transitions to the off state, charging of the capacitor C22 begins, and when the voltage of the capacitor C22 reaches a high level due to charging, an error signal (high level) is output.

The time required for the voltage of the capacitor C22 to reach a high level by charging is the OCP cutoff time T _OCP22 that masks the detection of an overcurrent. That is, the switch element Q22, the resistor R22, and the capacitor C22 function as a cutoff time generating circuit that generates the OCP cutoff time T _OCP22 . The OCP cutoff time T _OCP22 is set to a time shorter than the OCP cutoff time T _OCP21 (T _OCP22 <T _OCP21 ). The time constant of the resistor R22 and the capacitor C22 is set to a value smaller than the time constant of the resistor R21 and the capacitor C21. Therefore, when the OCP voltage value V _OCP exceeds the OCP threshold value Vref22, it also exceeds the OCP threshold value Vref21 and charging of the capacitor C21 begins, but if the voltage of the capacitor C22 reaches a high level by charging before the OCP cutoff time T _OCP21 has elapsed, an error signal (high level) is output. If the OCP voltage value _{V_OCP} becomes equal to or lower than the OCP threshold value Vref22 before the OCP shutoff time _{T_OCP22} has elapsed, the switch element Q22 transitions to the on state, the voltage of the capacitor C22 is discharged, and no error signal (high level) is output.

A series circuit consisting of a resistor R23 and a switch element Q23 is connected between the internal voltage Reg and the common line, and a capacitor C23 is connected in parallel to the switch element Q23. The output terminal of the comparator CMP23 is connected to the control terminal of the switch element Q23 via an inverter INV23. Therefore, when the OCP voltage value V _OCP exceeds the OCP threshold value Vref23, the comparator CMP23 outputs a high level (the inverter INV23 outputs a low level), and the switch element Q23 transitions to the OFF state. When the switch element Q23 transitions to the OFF state, charging of the capacitor C23 begins, and when the voltage of the capacitor C23 reaches a high level due to charging, an error signal (high level) is output.

The time required for the voltage of the capacitor C23 to reach a high level by charging is the OCP cutoff time T _OCP23 that masks the detection of an overcurrent. That is, the switch element Q23, the resistor R23, and the capacitor C23 function as a cutoff time generating circuit that generates the OCP cutoff time T _OCP23 . The OCP cutoff time T _OCP23 is set to a time shorter than the OCP cutoff time T _OCP22 (T _OCP23 <T _OCP22 ). The time constant of the resistor R23 and the capacitor C23 is set to a value smaller than the time constant of the resistor R22 and the capacitor C22. Therefore, when the OCP voltage value V _OCP exceeds the OCP threshold value Vref23, it also exceeds the OCP threshold value Vref22 and charging of the capacitor C22 is started, but if the voltage of the capacitor C23 reaches a high level by charging before the OCP cutoff time T _OCP22 has elapsed, an error signal (high level) is output. If the OCP voltage value _{V_OCP} becomes equal to or lower than the OCP threshold value Vref23 before the OCP shutoff time _{T_OCP23} has elapsed, the switch element Q23 transitions to the on state, the voltage of the capacitor C23 is discharged, and no error signal (high level) is output.

The voltages of capacitors C21 to C23 are input to the first to third input terminals of OR circuit OR21, respectively. The output terminal of OR circuit OR21 is connected to the other input terminal of AND circuit AND21, and when the AND circuit AND21 is in the on state, an error signal is output from overcurrent protection circuit 10 when the voltage of any of capacitors C21 to C23 reaches a high level. The error signal from overcurrent protection circuit 10 is input to control unit 20 built into low-side driver IC4 and is also output from error signal output terminal FO. When an error signal is input from overcurrent protection circuit 10, control unit 20 stops the on/off driving of low-side switching element QL and switches low-side switching element QL to a cut-off (off) state.

The variable voltage source 211 sets the OCP threshold Vref21 based on a user setting value _VBTMS input to a user setting terminal BTMS. With reference to Fig. 5, the variable voltage source 211 has a series circuit made up of resistors R50 and R54 connected between the internal voltage Reg and the common line, and outputs the voltage at the connection point between the resistors R50 and R54 as the OCP threshold Vref21.

The resistor R54 is connected in parallel to a series circuit consisting of resistor R51 and switch element Q51, a series circuit consisting of resistor R52 and switch element Q52, and a series circuit consisting of resistor R53 and switch element Q53. Therefore, the voltage of the OCP threshold Vref21 changes depending on the state of the switch elements Q51, Q52, and Q53.

The switch elements Q51, Q52, and Q53 are each composed of, for example, a MOS transistor. The control terminal of the switch element Q51 is connected to the output terminal of a comparator CMP51 that compares a user set value _VBTMS with a reference voltage Vref51, and the switch element Q51 is turned on when the user set value _VBTMS exceeds the reference voltage Vref51. The control terminal of the switch element Q52 is connected to the output terminal of a comparator CMP52 that compares the user set value _VBTMS with a reference voltage Vref52 (Vref51<Vref52) that is higher than the reference voltage Vref51, and the switch element Q52 is turned on when the user set value _VBTMS exceeds the reference voltage Vref52. The control terminal of the switch element Q53 is connected to the output terminal of a comparator CMP53 which compares the user set value _VBTMS with a reference voltage Vref53 (Vref52<Vref53) which is higher than the reference voltage Vref52, and is turned on when the user set value _VBTMS exceeds the reference voltage Vref53. Thus, when the user set value _VBTMS is equal to or lower than the reference voltage Vref51, all of the switch elements Q51, Q52, and Q53 are in the off state, when the user set value _VBTMS exceeds the reference voltage Vref51 and is equal to or lower than the reference voltage Vref52, only the switch element Q51 is in the on state, when the user set value _VBTMS exceeds the reference voltage Vref52 and is equal to or lower than the reference voltage Vref53, the switch elements Q51 and Q52 are in the on state, and when the user set value _VBTMS exceeds the reference voltage Vref53, all of the switch elements are in the on state. As a result, the OCP threshold Vref21 is set to a lower voltage as the user-set value V _BTMS is higher.

The reference voltage Vref53 is set to a voltage at which the input judgment of the AND circuit AND11 and the inverter INV20 is at a low level. Therefore, when the second overcurrent protection circuit 21 is selected, the variable voltage source 211 can set the OCP threshold Vref21 to a plurality of voltages based on the user setting value _VBTMS . In the configuration example of the variable voltage source 211 shown in FIG. 5, the OCP threshold Vref21 can be changed to four different voltages according to the user setting value _VBTMS . The number of voltages to which the OCP threshold Vref21 can be changed can be set appropriately.

Variable voltage sources

212 and 213 have the same configuration as variable voltage source 211, and set OCP thresholds Vref22 and Vref23, respectively, based on a user-set value _VBTMS . However, when the user-set value _VBTMS is the same, the resistance values of

variable voltage sources

211, 212, and 213 are set so that the above-mentioned relationship (Vref21<Vref22<Vref23) is maintained.

6A, the OCP thresholds Vref21, Vref22, and Vref23 set when the user-set value _VBTMS satisfies Vref51< _VBTMS ≦Vref52 are 1.0 V, 1.8 V, and 2.6 V, respectively. In this case, when the OCP voltage value _VOCP is 0.9 V (current detection element Rs=50 mΩ and 18 A), _VOCP ≦Vref21, so the second overcurrent protection circuit 21 does not execute the OCP operation. When the OCP voltage value _VOCP is 1.65 V (current detection element Rs=50 mΩ and 33 A), Vref21< _VOCP ≦Vref22, so the second overcurrent protection circuit 21 outputs an error signal when the OCP cutoff time _TOCP21 (e.g., 2 μs) has elapsed in a state where Vref21< _VOCP . At an OCP voltage value V _OCP =2.3V (46A with current detection element Rs=50mΩ), Vref22<V _OCP ≦Vref23, so the second overcurrent protection circuit 21 outputs an error signal when the OCP cutoff time T _OCP22 (e.g., 1 μs) has elapsed in a state where Vref22<V _OCP . Note that at an OCP voltage value V _OCP =2.3V, Vref23<V _OCP , so the second overcurrent protection circuit 21 outputs an error signal even if the OCP cutoff time T _OCP21 (e.g., 2 μs) has elapsed in a state where Vref11<V _OCP. However, since the error signal after the elapse of T _OCP22 has already been input to the control unit 20, the low-side switching element QL is already in the off state.

6B, the OCP thresholds Vref21, Vref22, and Vref23, which are set when the user-set value _VBTMS is Vref52< _VBTMS ≦Vref53, are 0.8 V, 1.6 V, and 2.4 V, respectively. In this case, when the OCP voltage value V _OCP =0.9 V, Vref21<V _OCP ≦Vref22, so the second overcurrent protection circuit 21 outputs an error signal when the OCP cutoff time T _OCP21 (e.g., 2 μs) has elapsed in a state where Vref21<V _OCP . At OCP voltage values V _OCP =1.65 V and 2.3 V, Vref22<V _OCP ≦Vref23, so the second overcurrent protection circuit 21 outputs an error signal when the OCP cutoff time T _OCP22 (e.g., 1 μs) has elapsed in a state where Vref22<V _OCP . Note that at OCP voltage values V _OCP =1.65 V and 2.3 V, Vref21<V _OCP , so the second overcurrent protection circuit 21 outputs an error signal even if the OCP cutoff time T _OCP21 (e.g., 2 μs) has elapsed in a state where Vref21<V _OCP . However, since the error signal after the elapse of T _OCP22 has already been input to the control unit 20, the low-side switching element QL is already in the off state.

6C, the OCP thresholds Vref21, Vref22, and Vref23 set when the user-set value _VBTMS is Vref53< _VBTMS are 0.6 V, 1.4 V, and 2.2 V, respectively. In this case, when the OCP voltage value V _OCP =0.9 V, Vref21<V _OCP ≦Vref22, so the second overcurrent protection circuit 21 outputs an error signal when the OCP cutoff time T _OCP21 (e.g., 2 μs) has elapsed in a state where Vref21<V _OCP . When the OCP voltage value V _OCP =1.65 V, Vref22<V _OCP ≦Vref23, so the second overcurrent protection circuit 21 outputs an error signal when the OCP cutoff time T _OCP22 (e.g., 1 μs) has elapsed in a state where Vref22<V _OCP . Note that, since Vref21< _VOCP at the OCP voltage value _VOCP =1.65V, the second overcurrent protection circuit 21 outputs an error signal even if the OCP cut-off time _TOCP21 (e.g., 2µs) has elapsed in a state where Vref21< _VOCP , but the low-side switching element QL is already in the OFF state because the error signal after _TOCP22 has elapsed has already been input to the control unit 20. At the OCP voltage value _VOCP =2.3V, Vref23< _VOCP , so the second overcurrent protection circuit 21 outputs an error signal when the OCP cut-off time _TOCP23 (e.g., 0.3µs) has elapsed in a state where Vref23< _VOCP . Note that, since the OCP voltage value V _OCP = 2.3V also satisfies Vref21 < V _OCP , the second overcurrent protection circuit 21 outputs an error signal even after the OCP cut-off time T _OCP21 (e.g., 2 μs) has elapsed in a state where Vref21 < V _OCP , but the low-side switching element QL is already in the OFF state because the error signal after T _OCP23 has already been input to the control unit 20. Similarly, since the OCP voltage value V _OCP = 2.3V also satisfies Vref22 < V _OCP , the second overcurrent protection circuit 21 outputs an error signal even after the OCP cut-off time T _OCP22 (e.g., 1 μs) has elapsed in a state where Vref22 < V _OCP , but the low-side switching element QL is already in the OFF state because the error signal after T _OCP23 has already been input to the control unit 20.

With the above configuration, in the second overcurrent protection circuit 21, the levels of the OCP thresholds Vref21, Vref22, and Vref23 to be compared with the OCP voltage value V _OCP are changed according to the user set value V _BTMS . The OCP thresholds Vref21, Vref22, and Vref23 are set to lower voltages as the user set value V _BTMS is higher. Different OCP cutoff times TOCP21, TOCP22, and TOCP23 are set for the OCP thresholds _Vref21 , _Vref22 , and _Vref23 , respectively. The OCP thresholds Vref21, Vref22, and Vref23 are set such that Vref21<Vref22<Vref23, and the OCP cutoff times T _OCP21 , T _OCP22 , and T _OCP23 are set such that T _OCP21 > T _OCP22 > T _OCP23 .

7 is a modified example of the second overcurrent protection circuit 21. In the second overcurrent protection circuit 21a, a select circuit 60 is interposed on the input side of an OR circuit OR21. The select circuit 60 selects one of the OCP cut-off times T _OCP21 , T _OCP22 , and T _OCP23 according to a select signal V _SEL input from a select signal input terminal SEL.

8, the select circuit 60 includes comparators CMP61, CMP62, and CMP63 which compare the select signal _VSEL with different reference voltages Vref61, Vref62, and Vref63 (reference voltages Vref61<Vref62<Vref63), respectively.

The outputs of comparators CMP61, CMP62, CMP63 are input to one input terminal of AND circuits AND61, AND62, AND63, respectively, and are also input to the first to third input terminals of NOR circuit NOR61. The output of NOR circuit NOR61 is input to one input terminal of AND circuits AND70, AND71, AND72. The voltage of capacitor C21 is input signal IN1, the voltage of capacitor C22 is input signal IN2, and the voltage of capacitor C23 is input signal IN3, which are input to the other input terminals of AND circuits AND61, AND62, AND63, respectively, and to the other input terminals of AND circuits AND70, AND71, AND72, respectively. The outputs of the AND circuits AND70, AND71, and AND72 are input to one input terminal of the OR circuits OR61, OR62, and OR63, respectively, and the outputs of the OR circuits OR61, OR62, and OR63 are output as output signals OUT1, OUT2, and OUT3, respectively.

The output of comparator CMP61 is also input to one input terminal of XOR circuit XOR61. The output of comparator CMP62 is also input to the other input terminal of XOR circuit XOR61 and one input terminal of XOR circuit XOR62. The output of comparator CMP63 is also input to the other input terminal of XOR circuit XOR62.

The output of XOR circuit XOR61 is input to one input terminal of AND circuit AND66, the output of AND circuit AND61 is input to the other input terminal of AND circuit AND66, and the output of AND circuit AND66 is input to the other input terminal of OR circuit OR61. The output of XOR circuit XOR62 is input to one input terminal of AND circuit AND68, and the output of AND circuit AND62 is input to the other input terminal of AND circuit AND68. The output of AND circuit AND68 is input to the other input terminal of OR circuit OR62. The output of AND circuit AND63 is input to the other input terminal of OR circuit OR63.

When the select signal _VSEL is _VSEL ≦ Vref61, the AND circuits AND61, AND62, and AND63 are turned off, and the AND circuits AND70, AND71, and AND72 are turned on. Therefore, as shown in Fig. 9, the input signals IN1, IN2, and IN3 are output as they are as the output signals OUT1, OUT2, and OUT3. This state is the same OCP operation as the second overcurrent protection circuit 21.

When the select signal _VSEL is Vref61< _VSEL ≦Vref62, the AND circuits AND62, AND63, AND70, AND71, and AND72 are turned off, and the AND circuit AND61 is turned on. Therefore, as shown in Fig. 9, the input signals IN2 and IN3 are masked, and only the input signal IN1 that operates during the OCP cutoff time _TOCP21 is output as the output signal OUT1.

When the select signal _VSEL is Vref62< _VSEL ≦Vref63, the AND circuits AND63, AND70, AND71, and AND72 are turned off, and the AND circuits AND61 and AND62 are turned on. The output of the AND circuit AND61 is masked by the low-level output of the XOR circuit XOR61 turning off the AND circuit AND66. Therefore, as shown in FIG. 9, the input signals IN1 and IN3 are masked, and only the input signal IN2 operating at the OCP cutoff time T _OCP22 is output as the output signal OUT2.

When the select signal _VSEL is Vref63< _VSEL , the AND circuits AND70, AND71, and AND72 are turned off, and the AND circuits AND61, AND62, and AND63 are turned on. The output of the AND circuit AND61 is masked by the low-level output of the XOR circuit XOR61 turning the AND circuit AND66 off. The output of the AND circuit AND62 is masked by the low-level output of the XOR circuit XOR62 turning the AND circuit AND68 off. Therefore, as shown in FIG. 9, the input signals IN1 and IN2 are masked, and only the input signal IN3 operating at the OCP cutoff time T _OCP23 is output as the output signal OUT3.

With the above configuration, the second overcurrent protection circuit 21a can also change the levels of the OCP thresholds Vref21, Vref22, and Vref23 that are compared with the OCP voltage value V _OCP using the user set value V _BTMS , and can select one of the OCP cut-off times T _OCP21 , T _OCP22 , and T _OCP23 using the select signal V _SEL .

As described above, this embodiment provides an overcurrent protection circuit 10 that detects a current flowing through a low-side switching element QL (switching element) connected between a motor power supply voltage Vpp (main power supply voltage) and a common line as an OCP voltage value V OCP, compares the OCP voltage value V _OCP with an OCP threshold value Vref, and detects an overcurrent when the OCP cut-off time T _OCP has elapsed in a state in which the OCP voltage value V _OCP exceeds the _OCP threshold value Vref. The overcurrent protection circuit 10 includes a plurality of comparators CMP11, CMP12, CMP13 that compare the OCP voltage value V _OCP with a plurality of different OCP threshold values Vref11, Vref12, Vref13, respectively, and sets different OCP cut-off times T _OCP11 , T _OCP12 , T _{The circuit} includes a plurality of cut-off time generating circuits [(switch element Q11, resistor R11, and capacitor C11), (switch element Q12, resistor R12, and capacitor C12), (switch element Q13, resistor R13, and capacitor C13)] that generate OCP13, and the cut-off time generating circuits generate OCP cut-off times TOCP11, TOCP12, and TOCP13 (TOCP11 > TOCP12 > TOCP13) for the OCP thresholds Vref11, Vref12, and Vref13 ( _Vref11 < _Vref12 < _Vref13 ) of comparators _CMP11 , _CMP12 , and _CMP13 , respectively.
With this configuration, overcurrent protection circuit 10 can detect overcurrent with multiple OCP cutoff times TOCP11, TOCP12, TOCP13 that are appropriately set according to multiple OCP thresholds _Vref11 , _Vref12 , _Vref13 , respectively. Therefore, it is possible to detect how susceptible a state is to thermal destruction and appropriately control the OCP cutoff time, and thus it is possible to accommodate a variety of switching elements that have different times until thermal destruction in the event of an abnormality. Because overcurrent protection circuit 10 is highly versatile, it is possible to reduce the variety, development time, and man-hours, and it also helps prevent installation errors.

Furthermore, in this embodiment, an input of a power supply voltage value V _OVM (main power supply voltage value) obtained by dividing the motor power supply voltage Vpp is accepted, and the OCP threshold value Vref is set to a lower voltage as the power supply voltage value V _OVM is higher.
With this configuration, the OCP thresholds Vref11, Vref12, and Vref13 are set to appropriate levels according to the motor power supply voltage Vpp, making the configuration more versatile.

Furthermore, in this embodiment, an input of a temperature voltage value _VVT (temperature detection value) of the temperature detected by the temperature sensor 6 is accepted, and the OCP threshold value Vref is set to a lower voltage as the temperature voltage value _VVT is lower (the temperature detected by the temperature sensor 6 is higher).
With this configuration, the OCP thresholds Vref11, Vref12, and Vref13 are set to appropriate levels according to the temperature detected by the temperature sensor 6, making the configuration more versatile.

Furthermore, in this embodiment, an input of a user-set value V _BTMS is accepted, and the OCP threshold value Vref is changeable based on the user-set value V _BTMS .
This configuration allows the user to set the OCP thresholds Vref11, Vref12, and Vref13 to appropriate levels, making it more versatile.

Furthermore, in this embodiment, a select circuit 60 is provided that receives an input of a select signal V _SEL and enables only one of the OCP cutoff times T _OCP11 , T _OCP12 , and T _OCP13 selected by the select signal V _SEL .
This configuration allows the user to select an appropriate OCP cutoff time T _OCP , making it more versatile.

The present embodiment also provides an overcurrent protection circuit 10 that detects a current flowing through a low-side switching element QL (switching element) connected between a motor power supply voltage Vpp (main power supply voltage) and a common line as an OCP voltage value V _OCP , compares the OCP voltage value V _OCP with an OCP threshold value Vref, and detects an overcurrent when an OCP cut-off time T _OCP has elapsed in a state in which the OCP voltage value V _OCP exceeds the OCP threshold value Vref, the overcurrent protection circuit 10 including a first overcurrent protection circuit 11 and a second overcurrent protection circuit 21. The first overcurrent protection circuit 11 includes a plurality of comparators CMP11, CMP12, CMP13 (first comparators) that compare the OCP voltage value V _OCP with a plurality of different OCP threshold values Vref11, Vref12, Vref13, respectively, and a plurality of comparators CMP11, CMP12, CMP13 that respectively set different OCP cut-off times T _OCP11 , T and a plurality of first cut-off time generating circuits [( _switch element Q11, resistor R11, and _capacitor C11), (switch element Q12, resistor R12, and capacitor C12), (switch element Q13, resistor R13, and capacitor C13)] for generating OCP cut-off times TOCP11, TOCP12, and TOCP13 (TOCP11 > _TOCP12 >TOCP13) for the OCP threshold values _Vref11 , Vref12, and Vref13 (Vref11<Vref12< _Vref13 ) of the comparators _CMP11 , _CMP12 , and _CMP13 , respectively, and generating a power supply voltage value _VOVM obtained by dividing the motor power supply voltage Vpp. The second overcurrent protection circuit 21 receives an input of a temperature voltage value _VVT (temperature detection value) of the temperature detected by the temperature sensor 6, and sets the OCP threshold value Vref to a lower voltage as the temperature voltage value _VVT is lower (the temperature is higher). The second overcurrent protection circuit 21 includes a plurality of comparators CMP21, CMP22, _CMP23 (second comparators) that compare the OCP voltage value _VOCP with a plurality of different OCP threshold values Vref21, Vref22, Vref23, respectively, and sets different OCP cut-off times _TOCP21 , TOCP22, TOCP23 for each of the plurality of comparators CMP21, _CMP22 , CMP23. and a plurality of second cut-off time generating _circuits [(switching element Q21, resistor R21, and capacitor C21), (switching element Q22, resistor R22, and capacitor C22), (switching element Q23, resistor R23, and capacitor C23)] that generate OCP23. The cut-off time generating circuits generate OCP cut-off times TOCP21, TOCP22, and TOCP23 (TOCP21>TOCP22>TOCP23) for the OCP threshold values Vref21, Vref22, and Vref23 ( _Vref21 < _Vref22 < _Vref23 ) of the comparators _CMP21 , _CMP22 , and _CMP23 , respectively, and generate an OCP voltage value V The power supply circuit includes a plurality of comparators that respectively compare _{an OCP} with a plurality of different OCP thresholds, and a plurality of cut-off time generation circuits that generate different OCP cut-off times for each of the plurality of comparators, wherein the cut-off time generation circuit generates a shorter OCP cut-off time the higher the OCP threshold of the comparator is, and receives an input of a user setting value _VBTMS , and the OCP threshold Vref is changeable based on the user setting value _VBTMS , and a first overcurrent protection circuit 11 and a second overcurrent protection circuit 21 detect an overcurrent with either one selected based on the user setting value _VBTMS .
With this configuration, an overcurrent can be detected by either the first overcurrent protection circuit 11, which can set the OCP thresholds Vref11, Vref12, Vref13 to appropriate levels in accordance with the motor power supply voltage Vpp and the temperature voltage value _VVT , or the second overcurrent protection circuit 21, which can set the OCP thresholds Vref21, Vref22, Vref23 to appropriate levels by the user, thereby making the configuration more versatile.

It is clear that the present invention is not limited to the above-described embodiments, and that each embodiment can be modified as appropriate within the scope of the technical concept of the present invention. Furthermore, the number, position, shape, etc. of the above-described components are not limited to the above-described embodiments, and the number, position, shape, etc. can be any suitable number for implementing the present invention. The same components are denoted by the same reference numerals in each drawing.

1 Motor 2 Inverter circuit 3 High side driver IC
4 Low side driver IC
5. Controller
10: overcurrent protection circuit 11: first overcurrent protection circuit 20: control unit
21, 21a Second overcurrent protection circuit 60 Select circuit (select)
111, 112, 113, 211, 212, 213 Variable voltage source

Claims

1. An overcurrent protection circuit that detects a current flowing through a switching element connected between a main power supply voltage and a common line as an OCP voltage value, compares the OCP voltage value with an OCP threshold value, and detects an overcurrent when an OCP cutoff time has elapsed in a state in which the OCP voltage value exceeds the OCP threshold value,
a plurality of comparators for comparing the OCP voltage value with a plurality of different OCP thresholds, respectively;
a plurality of cut-off time generating circuits that generate different OCP cut-off times for the plurality of comparators,
The overcurrent protection circuit according to claim 1, wherein the cutoff time generating circuit generates a shorter OCP cutoff time as the OCP threshold of the comparator becomes higher.
The overcurrent protection circuit of claim 1, characterized in that it accepts an input of a main power supply voltage value obtained by dividing the main power supply voltage, and the OCP threshold is set to a lower voltage as the main power supply voltage is higher.
The overcurrent protection circuit according to claim 1 or 2, characterized in that it accepts input of a temperature detected by a temperature sensor, and the higher the temperature, the lower the OCP threshold voltage is set.
The overcurrent protection circuit of claim 1, characterized in that it accepts input of a user-set value, and the OCP threshold value is changeable based on the user-set value.
The overcurrent protection circuit of claim 1, further comprising a select circuit that accepts a select signal input and enables only the OCP cutoff time selected by the select signal.
1. An overcurrent protection circuit that detects a current flowing through a switching element connected between a main power supply voltage and a common line as an OCP voltage value, compares the OCP voltage value with an OCP threshold value, and detects an overcurrent when an OCP cutoff time has elapsed in a state in which the OCP voltage value exceeds the OCP threshold value,
A first overcurrent protection circuit and a second overcurrent protection circuit are provided.
The first overcurrent protection circuit comprises:
a plurality of first comparators each for comparing the OCP voltage value with a plurality of different OCP thresholds;
a plurality of first cut-off time generating circuits that generate different OCP cut-off times for the plurality of first comparators,
the first cut-off time generating circuit generates a shorter OCP cut-off time as the OCP threshold of the first comparator is higher;
an input of a main power supply voltage value obtained by dividing the main power supply voltage is received, and the OCP threshold is set to a lower voltage as the main power supply voltage is higher;
receiving an input of a temperature detected by a temperature sensor, and setting the OCP threshold to a lower voltage as the temperature increases;
The second overcurrent protection circuit includes:
a plurality of second comparators that respectively compare the OCP voltage value with a plurality of different OCP thresholds;
a plurality of second cutoff time generating circuits that generate different OCP cutoff times for the plurality of second comparators,
the second cut-off time generating circuit generates a shorter OCP cut-off time as the OCP threshold of the second comparator is higher;
An input of a user-set value is accepted, and the OCP threshold value is changeable based on the user-set value;
An overcurrent protection circuit, wherein the first overcurrent protection circuit and the second overcurrent protection circuit detect an overcurrent in one of them selected based on the user set value.
A semiconductor device in which the overcurrent protection circuit according to claim 1 or 6 is integrated on a substrate.