JP5585520B2 - Load drive device - Google Patents

Description

  The present invention relates to a load driving device having a power element composed of a semiconductor switching element that controls current supply to a load and a clamp circuit that clamps a driving voltage of the power element to a constant voltage.

  2. Description of the Related Art Conventionally, a configuration in which a clamp circuit that clamps a gate voltage is provided in a load driving device that controls current supply to a load by driving a power element is known. When driving a power element, if the power supply and GND are short-circuited, an overcurrent state occurs, and if the overcurrent reaches a size outside the safe operating area that exceeds the element withstand capability, the element may be destroyed. . For this reason, the gate voltage is clamped by the clamp circuit to bring the power element into a half-on state, thereby preventing element destruction due to overcurrent flowing (see, for example, Patent Document 1). In a load driving device having the ability to drive a plurality of power elements, a plurality of such clamp circuits are provided according to the number of power elements.

JP-A-10-032476

  However, in a load driving device having the ability to drive a plurality of power elements, a part of the power elements may not be used. For example, the amount of current supplied to the load may be reduced depending on the type of load, and power elements are provided in parallel, and when the load driving device is applied to a load with a large amount of current supplied in parallel. When a plurality of power elements provided are used and the current supply amount is applied to a small load, only a part of the plurality of power elements provided in parallel is used. In this case, only a smaller number of power elements than the number of clamp circuits are driven.

  In such a case, there will be a clamp circuit that is not used, and the clamp circuit will be in the output open state, but the same state will be maintained even if the power element actually used and the clamp circuit are disconnected. Become. For this reason, it is impossible to determine whether the clamp circuit is in an unused state or in a disconnected state in the portion (IC) that is monitoring disconnection.

  In view of the above points, the present invention is to enable determination of whether a clamp circuit is in an unused state or a disconnected state in a case where only a smaller number of power elements than the number of clamp circuits are driven. Objective.

  In order to achieve the above object, the invention according to claim 1 is in a clamped state based on the potential of the clamp terminals (11a to 11c) to which the potential of the control terminal (1b) of the power element (1a) is input. And a clamp disconnection control circuit (55) for detecting a disconnection state of a path from the control terminal (1b) through the clamp circuit (5a to 5c), and the temperature detection circuit (7a to 7c) includes a temperature sensor (1h). An overheat detection circuit (71) for detecting an overheat state of the power element (1a) based on the potential of the temperature detection terminals (14a to 14c) to which the is connected, a temperature sensor (1h), and temperature detection terminals (14a to 14c) A disconnection detection circuit (72) for detecting a disconnection state between the two, and a disconnection detection invalidation circuit (73) for detecting a disconnection invalid state in which the temperature sensor (1h) is not connected to the temperature detection terminals (14a to 14c). When a disconnection invalid state is detected, the clamp disconnection control circuit (55) is configured to output a signal indicating that to the clamp disconnection control circuit (55). The clamp disconnection control circuit (55) includes the temperature detection circuits (7a to 7c). ) Disconnection detection invalidation circuit (73) receives a signal that is output when a disconnection invalid state is detected, and when this signal is input, it is not the disconnection state of the path through the clamp circuits (5a to 5c), but the clamp It is characterized by determining that the circuit (5a-5c) is in a disconnection invalid state.

  In this way, using the temperature detection terminals (14a to 14c) to which the output of the temperature sensor (1h) is input, a part of the clamp circuits (5a to 5c) and the temperature detection circuits (7a to 7c) are power elements ( When not connected to 1a) or the temperature sensor (1h), a disconnection invalid state in which the temperature sensor (1h) is not connected is detected based on the potential of the temperature detection terminals (14a to 14c). By doing in this way, when detecting disconnection based on the potential of the clamp terminals (11a to 11c) connected to the clamp circuits (5a to 5c), the temperature detection terminal determines whether the disconnection state or the disconnection invalid state. The determination can be made according to the potentials (14a to 14c). Therefore, it is possible to accurately determine whether the clamp terminals (11a to 11c) are in a disconnected state or an output open state.

  Therefore, when only a smaller number of power elements (1a) are driven than the number of clamp circuits (5a to 5c), it is determined whether the clamp circuits (5a to 5c) are in an unused state or a disconnected state. It becomes possible to do.

  In the invention described in claim 2, the clamp disconnection control circuit (55) includes a control signal (8) for controlling on / off of the gate driver circuit (3) and the gate-off circuit (4), and a temperature detection circuit (7a-7c). Of the clamp terminal (11a to 11c) and the clamp terminal (11a to 11c) are determined to be in a clamped state, a disconnected state, or a disconnected state, and a disconnection is detected when the gate-off circuit (4) is turned on by a control signal. When the signal output when the disconnection invalid state is detected from the invalidation circuit (73) is input, the clamp circuits (5a to 5c) are determined to be in the disconnection invalid state.

  Thus, when the gate-off circuit (4) is turned on by the control signal, the disconnection can be detected based on the potentials of the clamp terminals (11a to 11c). In this case, if a signal to be output when the disconnection invalidation state is detected from the disconnection detection invalidation circuit (73) is input, it is assumed that the disconnection invalid state is detected. Thus, the disconnection state can be prevented from being detected.

  In the invention according to claim 3, in the temperature detection circuits (7a to 7c), the potential of the temperature detection terminals (14a to 14c) is outside the voltage range output from the output terminal (1f) of the temperature sensor (1h). The disconnection detection invalidation circuit (73) detects a disconnection invalid state, and outputs a signal indicating the fact to the clamp disconnection control circuit (55).

  As described above, the voltage outside the voltage range output from the output terminal (1f) of the temperature sensor (1h) is input to the temperature detection terminals (14a to 14c), so that the disconnection detection invalidation circuit (73) is disconnected. An invalid state can be detected.

  For example, as described in claim 4, the clamp disconnection control circuit (55) can be provided in the clamp circuits (5a to 5c).

In the invention according to claim 5, the gate driver circuit (3), the gate-off circuit (4), the clamp circuits (5a to 5c) and the temperature detection circuit (7a to 7c) are control ICs for controlling the power element (1a). The clamp disconnection control circuit (55) is also provided in the control IC (2).

  Thus, since the clamp disconnection control circuit (55) is provided in the control IC (2) used for driving the power element (1a), it can be integrated together with each circuit provided in the control IC (2). Easy configuration.

  The invention according to claim 6 is characterized in that the clamp disconnection control circuit (55) is constituted by CMOS logic.

  In this way, the clamp disconnection control circuit (55) can be configured by a logic circuit, and if the logic circuit is configured by CMOS logic, the chip area can be reduced.

  The invention according to claim 7 is characterized in that the control IC (2) is constituted by a semiconductor element circuit in which a bipolar transistor, a CMOS and a DMOS are combined.

  In this way, by configuring the control IC (2) with a semiconductor element circuit in which a bipolar transistor, CMOS, and DMOS are combined, it is possible to configure all analog circuits and digital circuits on one chip. For this reason, compared with the case where these must be comprised by another chip | tip, it becomes possible to aim at simplification of an apparatus more.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

It is the figure which showed the block structural example of the load drive device provided with the clamp circuit concerning 1st Embodiment of this invention. It is the figure which showed the specific circuit structural example of the power module 1 of the load drive device shown in FIG. FIG. 6 is a diagram showing details of the clamp circuit 5. 3 is a diagram showing details of a temperature detection circuit 7. FIG. It is a timing chart which summarized the magnitude relationship of various voltages and threshold value Vth1-Vth3. 5 is a truth table showing logic determination in the clamp disconnection control circuit 55. It is a truth table showing the relationship between the state of each terminal and the state of the load driving device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a diagram illustrating a block configuration example of a load driving apparatus including a clamp circuit according to the present embodiment. With reference to this figure, the load drive apparatus provided with the clamp circuit of this embodiment is demonstrated.

  The load driving device shown in FIG. 1 includes a power module 1 having a power element 1a for controlling on / off of current supply to a load, and a power module control IC 2 having various circuits for driving the power element 1a. It is set as the structure with these.

  The power element 1a is provided in a power supply line L that supplies current to the load. When the power element 1a is turned on, current is supplied to the load through the power line L and the load is driven. The power element 1a is configured by semiconductor switching such as an IGBT or a power MOSFET, and the on / off state is controlled by controlling the gate voltage. In the present embodiment, a diagram in which two power elements 1a are connected in parallel to the power supply line L is shown, but it may be only one, or may be three or more.

  FIG. 2 is a circuit schematic diagram in the case where the power element 1a is composed of an IGBT. As shown in this figure, the power element 1a has a control terminal 1b, a power supply terminal 1c, a reference potential terminal 1d, and a sense terminal 1e, and controls the voltage of the control terminal 1b, that is, the gate voltage. As a result, the power element 1a constituted by the IGBT is turned on, and the main current supplied to the load is caused to flow between the power supply terminal 1c and the reference potential terminal 1d. The sense terminal 1e flows a sense current that is reduced at a predetermined current mirror ratio with respect to the main current. The magnitude of the main current can be detected based on the sense current flowing through the sense terminal 1e.

  Further, the power module 1 is provided with a temperature sensor 1h, and the temperature of the power module 1, that is, the temperature of the power element 1a based on the output from the potential difference between the output terminal 1f of the temperature sensor 1h and the reference power supply terminal 1g. Can be detected. The temperature sensor 1h generates an output corresponding to the temperature of the power element 1a. For example, the temperature sensor 1h includes a bias current from the power module control IC 2 and a plurality of stages of diodes connected in series, and the forward voltage Vf of the diode is The output corresponding to the temperature of the power element 1a is changed from the output terminal 1f by utilizing the temperature characteristic.

  The power module control IC 2 includes a gate driver circuit 3, a gate-off circuit 4, a clamp circuit 5 (5a to 5c), a current detection circuit 6 (6a to 6c), a temperature detection circuit 7 (7a to 7c), and the like. . The power module control IC 2 supplies current to the load by turning on the power element 1a and turns off the power element 1a based on an IN signal for driving the load input from a microcomputer (not shown). Stop the current supply to.

  The power module control IC 2 is provided with various terminals 8 to 15 connected to various circuits 3 to 7 and the like incorporated therein, and the various terminals 8 to 15 are output terminals 1f and power of the temperature sensor 1h provided in the power element 1a. It is connected to the terminals 1b to 1e of the element 1a.

  Specifically, the power module control IC 2 includes an input terminal 8, an on output terminal 9, an off output terminal 10, a clamp terminal 11 (11a to 11c), a reference potential terminal 12, a current detection terminal 13 (13a to 13c), A temperature detection terminal 14 (14a to 14c) and a power supply terminal 15 are provided.

  The input terminal 8 receives an IN signal from a microcomputer (not shown). The IN signal input to the input terminal 8 is transmitted to the gate driver circuit 3 and the clamp circuit 5 so that the gate driver circuit 3 and the clamp circuit 5 can grasp that the power element 1a is turned on.

  The on output terminal 9 is used as an output terminal when the gate driver circuit 3 turns on the power element 1a, is connected to the output of the gate driver circuit 3, and is connected to the control terminal 1b of the power element 1a via the gate resistors 16a and 16b. Connected. The gate driver circuit 3 controls the gate voltage of the power element 1a via the ON output terminal 9. The off output terminal 10 is used to draw out the electric charge stored in the gate through the gate off circuit 4 when the application of the gate voltage by the gate driver circuit 3 is stopped. The off output terminal 10 is connected to the gate off circuit 4 and is connected to the control terminal 1b of the power element 1a through the gate resistor 16c.

  The clamp terminals 11 (11a to 11c) are provided corresponding to the respective clamp circuits 5 (5a to 5c), and are normally connected to the control terminal 1b of the power element 1a to clamp the gate voltage of the power element 1a. Used to do. The reference potential terminal 12 receives a negative reference potential of the load driving device. For example, when the load driving device is applied to an inverter for driving a motor, the power element 1a is disposed on either the high side or the low side of the motor, but is disposed on the high side of the motor. In this case, the reference potential is the high side potential of the motor, and when the reference potential is disposed on the low side of the motor, the reference potential is the GND potential. The reference potential terminal 12 is connected to the negative side of the gate-off circuit 4 and the clamp circuit 5.

  The current detection terminal 13 (13a to 13b) receives a sense current for detecting the main current of the power element 1a and transmits it to the current detection circuit 6 (6a to 6c). Moreover, the temperature detection terminal 14 (14a-14c) inputs the output of the temperature sensor 1h, and transmits it to the temperature detection circuit 7 (7a-7c). The power supply terminal 15 is connected to the power supply 17 and outputs the potential of the power supply 17.

  The power module control IC 2 of the present embodiment has a configuration in which three clamp circuits 5, three current detection circuits 6, and three temperature detection circuits 7 are provided so as to correspond to one provided with three power elements 1a. Therefore, the clamp terminal 11, the current detection terminal 13, and the temperature detection terminal 14 which are connected are provided with three each. However, in the present embodiment, the power module control IC 2 is applied when the number of power elements 1a is only two.

  In such a configuration, since the number of power elements 1a is smaller than the number of clamp circuits 5, two of the three clamp circuits 5 are used for clamping the gate voltage of the power element 1a. However, the remaining one is not used for clamping the gate voltage of the power element 1a. For this reason, in the present embodiment, the clamp terminal 11c is in an output open state, that is, a state in which neither is connected.

  Further, among the current detection terminals 13, the terminals 13 c and 14 c connected to the current detection circuit 6 c and the temperature detection circuit 7 c corresponding to the clamp circuit 5 c that does not clamp the power element 1 a are respectively connected to a reference potential or a power supply 17. It is designed to be connected to a wiring having a potential.

  Such a connection form constitutes a load driving device. In the load driving device configured as described above, the gate driver circuit 3 supplies power from the power source 17 based on the IN signal from the input terminal 8 to generate a gate voltage in the power element 1a. In the present embodiment, the gate driver circuit 3 is turned off when the IN signal is at a high level to turn off the power element 1a, and is turned on when the IN signal is at a low level to generate a gate voltage to turn on the power element 1a. .

  The gate-off circuit 4 extracts the electric charge stored in the gate of the power element 1a based on the IN signal input from the input terminal 8, and is controlled so that the on / off state is reversed with respect to the gate driver circuit 3. In the case of the present embodiment, the gate-off circuit 4 is turned on when the IN signal is at a high level, pulls out the electric charge stored in the gate of the power element 1a, and is turned off when the IN signal is at a low level, thereby turning on the power element 1a. Put it in a state.

  The clamp circuit 5 plays a role of clamping the gate voltage of the power element 1a to a clamp voltage smaller than the full-on state when driving the power element 1a. When the power element 1a is driven, if the power supply 17 that supplies current to the load and the GND are short-circuited, an overcurrent state occurs, and the overcurrent reaches a size outside the safe operation region that exceeds the element withstand capability. Then, there is a possibility of device destruction. For this reason, the clamp circuit 5 clamps the gate voltage to place the power element 1a in a half-on state, thereby preventing element destruction due to overcurrent flowing.

  FIG. 3 is a diagram showing details of the clamp circuit 5 in FIG. In this figure, only the part related to the control of one power element 1a in FIG. 1 is extracted and shown.

  As shown in this figure, the clamp circuit 5 includes a short circuit control circuit 50, a clamp control circuit 51, an impedance circuit 52, a comparator 53, a power supply circuit 54, a clamp disconnection control circuit 55, a comparator 56, a current supply unit 57, and Reference power sources 58 and 59 are provided.

  The short circuit control circuit 50 performs control at the time of a short circuit based on the detection result of the current detection circuit 6, and detects that the main current is an overcurrent by the current detection circuit 6 as will be described later. And an output for turning on the power supply circuit 54 from the short-circuit control circuit 50 based on the detection result.

  The clamp control circuit 51 is connected between the control terminal 1 b of the power element 1 a and the reference potential terminal 12, and is configured by a switch whose on / off is controlled based on the output of the comparator 53. The clamp control circuit 51 is configured by a semiconductor switching element such as a MOSFET, for example. When the clamp control circuit 51 is turned on, the clamp control circuit 51 tries to be supplied to the control terminal 1b by connecting the control terminal 1b of the power element 1a and the reference potential terminal 12. By absorbing energy and flowing it to the reference potential side, the gate voltage of the control terminal 1b is clamped to the clamp voltage.

  The impedance circuit 52 is used to increase the impedance so as to generate a potential difference when the clamp control circuit 51 is turned on. For example, as described above, the clamp control circuit 51 is configured by, for example, a MOSFET, but by arranging the impedance circuit 52 between the gate and the source of the MOSFET, a potential difference is formed between them, and the clamp control circuit 51 To be turned on.

  The comparator 53 compares the reference voltage VREF1 generated by the reference power supply 58 with the potential of the clamp terminal 11, that is, the gate voltage of the power element 1a, and generates a high-level output when the gate voltage becomes larger than the reference voltage VREF1. As a result, the voltage on the high side of the impedance circuit 52 is set to a high level, and the clamp control circuit 51 is turned on.

  The power supply circuit 54 controls the voltage application from the power source to the comparator 53. When the power supply circuit 54 is turned on, the voltage application to the comparator 53 is performed, thereby starting the comparator 53. It is supposed to be. On / off of the power supply circuit 54 is controlled based on the output of the short-circuit control circuit 50 based on the detection result of the current detection circuit 6, and the main current is overcurrent in the current detection circuit 6 as will be described later. When detected, the short-circuit control circuit 50 outputs an output for turning on the power supply circuit 54 based on the detection result. Although not shown in FIG. 3, the power supply circuit 54 is also turned on for a predetermined clamping period when the power element 1a is turned on by the IN signal from the input terminal 8. As a result, when the power element 1a is driven, the gate voltage is clamped to the clamp voltage, thereby preventing an overcurrent from occurring.

  The clamp disconnection control circuit 55 detects a disconnection of the clamp terminal 11 connected to the clamp circuit 5 and outputs a signal indicating the disconnection from the disconnection output terminal 18 at the time of disconnection. The clamp disconnection control circuit 55 is based on the output of the comparator 56 input to the terminal 55a, the output of the temperature detection circuit 7 input to the terminal 55b, and the IN signal from the input terminal 8 input to the terminal 55c. 11 disconnections are detected. Specifically, the clamp disconnection control circuit 55 is configured by a logic circuit such as CMOS logic, and whether the clamp terminal 11 is disconnected based on the logical operation of the signals input to the terminals 55a to 55c. It is determined whether the output is open. This logical operation will be described later in detail.

  The comparator 56 compares the potential of the clamp terminal 11, that is, the gate voltage of the power element 1 a with the reference voltage VREF 2 generated by the reference power supply 59, and outputs an output indicating the comparison result to the clamp disconnection control circuit 55. Specifically, the comparator 56 outputs a high level if the potential of the clamp terminal 11 is greater than the reference voltage VREF2, and outputs a low level if it is smaller. With such a structure, the clamp circuit 5 is configured.

  The current detection circuit 6 detects the magnitude of the main current of the power element 1a based on the sense current flowing through the sense terminal 1e of the power element 1a. When the current detection circuit 6 detects that the main current is an overcurrent, On the other hand, an instruction signal for clamping the gate voltage of the power element 1a is issued. For example, the current detection circuit 6 is configured by a comparator or the like that compares a value obtained by voltage-converting the sense current with a threshold voltage corresponding to the overcurrent. When the value obtained by converting the sense current exceeds the threshold voltage, power is supplied to the clamp circuit 5. A command signal for turning on the circuit 54 is output. Thereby, since the power supply circuit 54 is turned on, the gate voltage of the power element 1a is clamped to the clamp voltage, and the occurrence of overcurrent is suppressed.

  Whether the temperature detection circuit 7 generates an output corresponding to the temperature of the power element 1a, and when the power element 1a is at a high temperature, notifies the microcomputer (not shown) that the power element 1a is in an overheated state and stops driving the power element 1a. Alternatively, the power element 1a can be turned off by forcibly shutting off the gate driver circuit 3. However, in this embodiment, the temperature detection circuit 7 can also detect disconnection and open output. It is.

  FIG. 4 is a diagram showing details of the temperature detection circuit 7 in FIG. This figure also shows only the part related to the control of the two power elements 1a shown in FIG. In addition, although this figure shows and demonstrates the example which incorporated two of the three temperature detection circuits 7a-7c described in FIG. 1, it is set as the form containing all three actually. In addition, this figure shows a case where the temperature sensor 1h is configured by a multistage diode, and a case will be described in which the temperature of the power element 1a is detected based on the temperature characteristics of the forward voltage Vf of the multistage diode.

  As shown in FIG. 4, in the temperature detection circuit 7, when the battery voltage VB is applied from the power supply terminal 7a, the regulator 70 generates the drive voltage VCC based on the battery voltage VB, and operates based on the drive voltage VCC. To do. The temperature detection circuit 7 is connected to the output terminal 1f of the temperature sensor 1h of each power element 1a through connection terminals OH1 and OH2, and an overheat detection circuit 71 that performs overheat protection based on the potentials of the connection terminals OH1 and OH2. A disconnection detection circuit 72 that performs disconnection detection and a disconnection detection invalidation circuit 73 that disables disconnection detection are provided, and these are integrally configured as an IC.

  The overheat detection circuit 71 detects the overheat state of each power element 1a based on the potentials of the connection terminals OH1 and OH2, and outputs an instruction signal for clamping the gate voltage of the power element 1a when the overheat state is detected. Protect. The disconnection detection circuit 72 detects that the connection between the connection terminals OH1 and OH2 and the temperature sensor 1h is disconnected based on the potentials of the connection terminals OH1 and OH2, and when it is disconnected, the gate of the power element 1a is detected. The power element 1a is protected by issuing an instruction signal for clamping the voltage. The disconnection detection invalidation circuit 73 detects the output open state, and when it is detected, even if it is detected by the disconnection detection circuit 72, it is invalidated.

  The overheat detection circuit 71 includes constant current circuits 71a and 71b, comparators 71c and 71d, voltage dividing resistors 71e and 71f, and an overheat signal output circuit 71g. In the overheat detection circuit 71, constant currents are supplied from the constant current circuits 71a and 71b so that the potentials of the connection terminals OH1 and OH2 become the forward voltages Vf of the plurality of diodes constituting the temperature sensor 1h. . Since the forward voltage Vf of the plurality of diodes varies depending on the temperature of the power element 1a due to the temperature characteristics of the diodes, the potentials of the connection terminals OH1 and OH2 become values corresponding to the temperature of the power element 1a. Therefore, the overheated state of the power element 1a can be detected based on the potentials of the connection terminals OH1 and OH2.

  Specifically, the comparators 71c and 71d compare the potentials of the connection terminals OH1 and OH2 with the divided potential Vth1 obtained by dividing the drive voltage VCC by the voltage dividing resistors 71e and 71f (hereinafter referred to as overheat detection threshold). The result is output to the overheat signal output circuit 71g. Since the forward voltage Vf of the plurality of diodes decreases as the temperature of the power element 1a increases, when the power element 1a is not overheated, the input potentials of the connection terminals OH1 and OH2 form the voltage dividing resistors 71e and 71f. It becomes larger than the overheat detection threshold Vth1. For this reason, when the power element 1a is not overheated, the outputs of the comparators 71c and 71d are at a high level, and when overheated, the outputs of the comparators 71c and 71d are switched to a low level. Therefore, in the overheat signal output circuit 71g, when the output of any one of the comparators 71c and 71d becomes a low level, this is detected, and it is detected that at least one of the power elements 1a is in an overheat state, and the microcomputer is powered. The power element 1a can be turned off by outputting an instruction signal for stopping the driving of the element 1a or by forcibly shutting off the gate driver circuit 3. For example, the overheat signal output circuit 71g is configured by an AND circuit and outputs a low level as an instruction signal when the output of any of the comparators 71c and 71d becomes a low level.

  The disconnection detection circuit 72 includes comparators 72a and 72b, voltage dividing resistors 72c and 72d, and a disconnection signal output circuit 72e. In the disconnection detection circuit 72, disconnection detection is performed using the potential change of the connection terminals OH1 and OH2 based on the supply of constant current from the constant current circuits 71a and 71b provided in the overheat detection circuit 71.

  Specifically, the comparators 72a and 72b compare the potentials of the connection terminals OH1 and OH2 with the divided potential Vth2 obtained by dividing the drive voltage VCC by the voltage dividing resistors 72c and 72d (hereinafter referred to as disconnection detection threshold). The result is output to the disconnection signal output circuit 72d. The disconnection detection threshold Vth2 formed by the voltage dividing resistors 72c and 72d is higher than the forward voltage Vf of the plurality of diodes constituting the temperature sensor 1h and smaller than the drive voltage VCC.

  For this reason, when not in the disconnection state, the disconnection detection threshold Vth2 formed by the voltage dividing resistors 72c and 72d is larger than the potentials of the connection terminals OH1 and OH2, and a low level is output from the comparators 72a and 72b. When either of the connection terminals OH1 and OH2 is disconnected, the potential of the connection terminal OH1 and OH2 in the disconnected state rises to the drive potential VCC, so that the outputs of the comparators 72a and 72b become high level. .

  Therefore, in the disconnection signal output circuit 72e, when the output of any one of the comparators 72a and 72b becomes high level, this is detected, and it is detected that at least one of the connections with the temperature sensor 1h is in the disconnection state. A signal indicating that is output. For example, the disconnection signal output circuit 72e is configured by an OR circuit, and is configured to output a high level as a signal indicating a disconnection state when one of the outputs of the comparators 72a and 72b becomes a high level.

  In FIG. 3, only the wiring for transmitting the output signal of the disconnection detection invalidation circuit 73 described below of the temperature detection circuit 7 to the clamp disconnection control circuit 55 is shown, but the overheat state and the result of the disconnection detection are shown. The signal is input to the microcomputer or used to turn off the power element 1a as a signal for forcibly shutting off the gate driver circuit 3.

  The disconnection detection invalidating circuit 73 includes a Zener diode 73a, voltage dividing resistors 73b and 73c, a transistor 73d, and a resistor 73e. The Zener diode 73a sets the disconnection detection invalidation threshold Vth3. When the potential of the connection terminal OH2 becomes larger than the disconnection detection invalidation threshold Vth3, the Zener diode 73a exceeds the Zener breakdown voltage of the Zener diode 73a. Is activated. The disconnection detection invalidation threshold Vth3 is set to a value larger than the drive voltage VCC.

  FIG. 4 shows an example in which the connection terminals OH1 and OH2 are connected to the temperature sensor 1h of each power element 1a. However, if the number of power elements 1a to be driven is small, the connection terminal OH2 is connected to the temperature sensor 1h. Output may be left open. In such a case, by connecting the connection terminal OH2 that is in the output open state to a potential that is higher than the disconnection detection invalidation threshold Vth3, for example, battery voltage, the output open state is not broken. So that it can be distinguished.

  In such a state, when the potential of the connection terminal OH2 becomes larger than the disconnection detection invalidation threshold Vth3, the voltage exceeds the Zener breakdown voltage of the Zener diode 73a, so that a divided potential by the voltage dividing resistors 73b and 73c is generated. It is done. Based on this, the base current flows, the transistor 73d is turned on, and the potential between the resistor 73e and the transistor 73d changes when the transistor 73d is turned off. The potential between the resistor 73e and the transistor 73d is used as the output potential of the disconnection detection invalidating circuit 73 and transmitted to the disconnection signal output circuit 72e. Specifically, since the drive potential VCC is between the resistor 73e and the transistor 73d when the transistor 73d is off, the output potential is at a high level, and when the transistor 73d is on, the output potential is at a low level. This output potential is transmitted as an output signal of the disconnection detection invalidating circuit 73 to the clamp circuits 5a to 5c. Therefore, in the clamp circuits 5a to 5c, when the signal input to the terminal 55b is at a low level, the disconnection can be invalidated even if the disconnection is detected based on the potentials of the clamp terminals 11a to 11b.

  In this manner, the temperature detection circuit 7 performs overheat detection and disconnection detection. In addition, when the connection terminal OH2 is not connected to the temperature sensor 1h and is not used for temperature detection, a large voltage such as a battery voltage is applied to the connection terminal OH2, and the temperature detection circuit 7 is not disconnected but the output is open. It is possible to distinguish the status.

  Note that, as described above, in FIG. 4, the example provided with two of the temperature detection circuits 7 a to 7 c has been described as an example, but actually, the configuration includes three. In that case, the overheat detection circuit 71 is further provided with one each of the constant current circuits 71a, 71b and the comparators 71c, 71d one by one, and the disconnection detection circuit 72 is further provided with one similar to the comparators 72a, 72b, These may be connected to the temperature sensor 1h through a third connection terminal OH3 (not shown). In this case, the disconnection detection invalidation circuit 73 may be connected to a terminal that is not connected to the temperature sensor 1h among the connection terminals OH1 to OH3 provided in the plurality of temperature detection circuits 7a to 7c.

  FIG. 5 is a timing chart summarizing the magnitude relationships of various voltages and threshold values Vth1 to Vth3. This figure shows a state in which the temperature of the power element 1a gradually rises from a temperature T1 (for example, room temperature) that is not in an overheated state, exceeds a temperature Tth that is assumed to be in an overheated state, and reaches a temperature T2.

  As shown in this figure, when the power element 1a is at a temperature T1 where the power element 1a is not overheated, the forward voltages Vf of the plurality of diodes constituting the temperature sensor 1h are large, so that the potentials of the connection terminals OH1, OH2 are, for example, the potential V1. It becomes. When the temperature of the power element 1a reaches the temperature T2 that is equal to or higher than the overheated temperature Tth, the potentials of the connection terminals OH1 and OH2 become, for example, the potential V2.

  The overheat detection threshold Vth1, the disconnection detection threshold Vth2, and the disconnection detection invalidation threshold Vth3 are set based on these potentials V1 and V2. That is, the overheat detection threshold Vth1 is set to the output potential of the output terminal 1f of the temperature sensor 1h at the temperature Tth assumed to be an overheat state, and is within a voltage range that can be output from the temperature sensor 1h, that is, smaller than the potential V1. , A value larger than the potential V2. The disconnection detection threshold Vth2 is a potential outside the voltage range that can be output from the temperature sensor 1h, and is set larger than the potential V1 and smaller than the drive voltage VCC. The disconnection detection invalidation threshold Vth3 is larger than the disconnection detection threshold Vth2 and the drive voltage VCC, and is smaller than the voltage (here, battery voltage VB) applied when the connection terminal OH2 is in the output open state.

  When the threshold values Vth1 to Vth3 are set in this way, the temperature detection circuit 7 can detect an overheating state or a disconnection state, and a part of the plurality of temperature detection circuits 7a to 7c is not used. Even when the output is in the open state, it can be prevented that the disconnection state is erroneously detected.

  As described above, the load driving device according to the present embodiment is configured. Next, the state determination method for the load driving device configured as described above, that is, a state determination method for determining whether the state is the normal state, the disconnection state, or the disconnection invalid state will be described. The state determination is performed when the IN signal input to the input terminal 8 is set to the high level to turn on the gate-off circuit 4, turn off the gate driver circuit 3, and turn off the power element 1a. In this case, normally, since the gate voltage of the power element 1a becomes low level, the reference voltage VREF2 becomes higher than the potential of the clamp terminal 11, and the terminal 55a of the clamp disconnection control circuit 55 is low. The level will be entered. Based on this assumption, disconnection detection between the gate of the power element 1a and the terminal 10 is performed. With reference to FIG. 6 and FIG. 7, the state determination method of a load drive device is demonstrated.

  As described above, the clamp disconnection control circuit 55 is based on the logical operation of the output of the comparator 56 input to each of the terminals 55a to 55c, the output of the temperature detection circuit 7, and the IN signal from the input terminal 8. It is determined whether 11 is disconnected or the output is open.

  FIG. 6 is a truth table showing logic determination in the clamp disconnection control circuit 55. A specific logical operation and state determination method based on the level of the signal input to each terminal 55a to 55c of the clamp disconnection control circuit 55 will be described with reference to FIG.

  An IN signal from the microcomputer is input to the terminal 55c of the clamp disconnection control circuit 55. When the power element 1a is turned on, a low level (L) is input. When the power element 1a is turned off, a high level (H) is input. Is done. Therefore, the state is determined when the terminal 55c is at a high level.

  When the power element 1a is turned off, or when the clamp control circuit 51 is turned on and the gate voltage of the power element 1a is controlled to the clamp voltage, the reference voltage is higher than the potential of the clamp terminal 11. VREF2 is larger. For this reason, the output of the comparator 56 becomes low level, and the potential of the terminal 55a becomes low level. In contrast, when a disconnection occurs between the gate of the power element 1a and the clamp circuits 5a to 5c, the current path from the gate of the power element 1a disappears, and the reference voltage VREF2 is higher than the potential of the clamp terminal 11. Is smaller. In this case, the output of the comparator 56 becomes high level, and the potential of the terminal 55a becomes high level.

  Therefore, the potential level of the terminal 55a represents whether or not the power element 1a is turned off or the gate voltage is clamped, and also represents whether or not it is disconnected. That is, if the potential of the terminal 55a is low level, the disconnection does not occur and it is in a normal state, and if it is high level, the disconnection may occur.

  On the other hand, the output of the disconnection detection invalidation circuit 73 in the temperature detection circuit 7 is also input to the terminal 55 b of the clamp disconnection control circuit 55. The potential of the terminal 55b is low when the temperature detection circuit 7 is not connected to the temperature sensor 1h, that is, when the output is open, and when the temperature detection circuit 7 is in use. Become high level. Therefore, even if the potential of the terminal 55a is at a high level, if the potential of the terminal 55b is at a low level, this means that the clamp circuit 5 is not in use but is in an unused state.

  Therefore, as shown in FIG. 6, the disconnection detection is performed based on the potential levels of the terminals 55a and 55b on the assumption that the state is detected when the terminal 55c is at the high level. That is, when the terminal 55c is at a high level and the terminal 55a is at a low level, it is determined that the terminal 55b is in a normal state regardless of whether the terminal 55b is at a high level or a low level. Further, when the terminal 55c is at a high level and the terminal 55a is at a high level, if the potential of the terminal 55b is high, it is determined that the circuit is disconnected, and if the potential of the terminal 55b is low, it is determined that the disconnection is invalid. The This makes it possible to perform state determination. Note that when the terminal 55c is at a low level, the potential levels of the other terminals 55a and 55b are in an indefinite state, so that the normal state is determined regardless of the potential levels of the other terminals 55a and 55b.

  Based on the result of such state determination, the microcomputer outputs a low level when the disconnection output terminal 18 is determined as a disconnection state, and outputs a high level when it is determined as a normal state or a disconnection invalid state. It is possible to accurately notify the disconnection state.

  FIG. 7 is a truth table summarizing the relationship between the potential levels of the plurality of temperature detection terminals 14a to 14c, the potential levels of the clamp terminals 11a to 11c, and the state determination. In FIG. 6 described above, the operation of the clamp disconnection control circuit 55 in one clamp circuit 5 has been described. Here, the three clamp circuits 5a to 5c are potentials of the temperature detection terminals 14a to 14c and the clamp terminals 11a to 11c. A description will be given of what kind of state determination result is output in accordance with the level. Note that at least one of the clamp circuits 5 is used to drive the power element 1a, and therefore, here, a case where the clamp circuit 5a is used will be described as an example.

  The state detection is performed when the potential of the IN signal input to the input terminal 8 is high level, that is, when the potential of the terminal 55c is high level. Since the clamp circuit 5a is used, the temperature detection terminal 14a is at a high level that is an actual use voltage and is not at a low level that is a disconnection invalid voltage. At this time, if both the temperature detection terminals 14b and 14c are at a high level, it means that the clamp circuits 5b and 5c are being used. For this reason, if any one of the clamp terminals 11a to 11c is at a high level, it is determined that it is in a disconnected state, and if all the potentials at the clamp terminals 11a to 11c are at a low level, it is in a normal state. Determined.

  Further, when the temperature detection terminal 14b is at a high level and the temperature detection terminal 14c is at a low level, it means that the clamp circuit 5b is used and the clamp circuit 5c is not used. For this reason, it is determined that the disconnection is invalid for the clamp circuit 5c regardless of the potential of the clamp terminal 11c, and for any one of the clamp terminals 11a and 11b, the potential of the clamp circuits 5a and 5b is at a high level. It is determined that the wire is disconnected.

  Similarly, when the temperature detection terminal 14b is low level and the temperature detection terminal 14c is high level, it means that the clamp circuit 5b is not used and the clamp circuit 5c is used. For this reason, it is determined that the disconnection is invalid for the clamp circuit 5b regardless of the potential of the clamp terminal 11b. When the temperature detection terminal 14b is at a low level and the temperature detection terminal 14c is at a high level, if any one of the clamp terminals 11a and 11c is at a high level, it is determined that the wire is disconnected.

  Further, when both the temperature detection terminals 14b and 14c are at a low level, it means that the clamp circuits 5b and 5c are not used. Therefore, the clamp circuits 5b and 5c are set to the potentials of the clamp terminals 11b and 11c. Regardless, it is determined that the disconnection is invalid. In this case, only the state determination based on the potential of the clamp terminal 11a is performed. If the potential of the clamp terminal 11a is at a high level, it is determined that the wire is disconnected.

  When the input terminal 8 is at a low level, the temperature levels of the temperature detection terminals 14a to 14c and the clamp terminals 11a to 11c are indefinite, so that the normal state is determined regardless of the potential levels of these terminals. .

  As described above, in the present embodiment, the temperature detection terminals 14a to 14c to which the output of the temperature sensor 1h is input are used, and a part of the clamp circuits 5a to 5c and the temperature detection circuits 7a to 7c are connected to the power module 1. When not connected, the disconnection invalid state where the temperature sensor 1h is not connected is detected based on the potentials of the temperature detection terminals 14a to 14c. For example, the temperature detection terminals 14a to 14c are not connected to the temperature sensor 1h by applying a voltage equal to or higher than the disconnection detection invalidation threshold Vth3 to the terminals not connected to the temperature sensor 1h among the temperature detection terminals 14a to 14c. To detect. By doing in this way, when performing disconnection detection based on the potential of the clamp terminals 11a to 11c connected to the clamp circuits 5a to 5c, it is determined whether the temperature detection terminals 14a to 14c are in the disconnection state or the disconnection invalid state. The determination can be made according to the potential. Therefore, it is possible to accurately determine whether the clamp terminals 11a to 11c are in a disconnected state or an output open state.

  Therefore, in a case where only a smaller number of power elements 1a than the number of clamp circuits 5a to 5c are driven, it is possible to determine whether the clamp circuits 5a to 5c are unused or disconnected. .

(Other embodiments)
In the said embodiment, although the circuit configuration example of the power module 1 and the power module control IC2 was shown, these showed an example of a circuit configuration, Comprising: You may be set as another circuit configuration. For example, the number of power elements 1a and the number of clamp circuits 5a to 5c and temperature detection circuits 7a to 7c can be arbitrarily set, and the power elements are driven more than the number of clamp circuits 5a to 5c and temperature detection circuits 7a to 7c. The present invention can be applied when the number of la is smaller.

  Moreover, although the case where the clamp disconnection control circuit 55 is provided in the clamp circuits 5a to 5c has been described in the above embodiment, the clamp disconnection control circuit 55 may be configured separately from the clamp circuits 5a to 5c. Furthermore, although the clamp disconnection control circuit 55 is provided in the power module control IC 2, it may be provided separately. However, since the power module control IC 2 used for driving the power element 1a can be provided together with each circuit provided in the power module control IC 2, the configuration of the peripheral circuit can be facilitated.

  Further, in the above-described embodiment, the clamp disconnection control circuit 55 is configured by a logic circuit and configured by CMOS logic. However, the clamp disconnection control circuit 55 may be configured by logic other than CMOS logic. However, if the CMOS logic has a simple configuration, the chip area can be reduced.

  In the above embodiment, the power module control IC 2 is constituted by a semiconductor element circuit in which a bipolar transistor, CMOS and DMOS are combined. With such a configuration, all of the analog circuit and the digital circuit can be configured on one chip, so that the apparatus can be further simplified as compared with the case where these circuits must be configured on different chips. It becomes possible.

1 power module 1a power element 1f output terminal 1h temperature sensor 2 power module control IC
DESCRIPTION OF SYMBOLS 3 Gate driver circuit 4 Gate off circuit 5 Clamp circuit 6 Current detection circuit 7 Temperature detection circuit 8 Input terminal 9 On output terminal 10 Off output terminal 11 Clamp terminal 12 Reference potential terminal 13 Current detection terminal 14 Temperature detection terminal 15 Power supply terminal 17 Power supply 18 Disconnection output terminal 51 Clamp control circuit 55 Clamp disconnection control circuit 70 Regulator 71 Overheat detection circuit 72 Disconnection detection circuit 73 Disconnection detection invalidation circuit

Claims (7)

A power supply terminal ( 1c ) and a reference potential terminal that are provided in a power supply line (L) that supplies current to the load and that are connected to the power supply line (L) when a gate voltage is applied to the control terminal (1 b). A power element (1a) for controlling current supply to the load by controlling on / off between (1d),
A temperature sensor (1h) having an output terminal (1f) for generating an output corresponding to the temperature of the power element (1a) and a reference potential terminal (1g);
A gate driver circuit (3) for turning on the power element (1a) by applying a gate voltage to the control terminal (1b);
A gate-off circuit (4) for turning off the power element (1a) by extracting charges from the control terminal (1b);
A plurality of clamp circuits (5a to 5c) for clamping the gate voltage to a predetermined clamp voltage;
Temperature detection circuits (7a to 7c) provided corresponding to the number of the clamp circuits (5a to 5c) and detecting the temperature of the power element (1a) based on the output of the temperature sensor (1h), Prepared,
The number of the power elements (1a) is smaller than the number of the clamp circuits (5a to 5c) and the temperature detection circuits (7a to 7c), and the clamp circuit (5a to 5c) and the temperature detection circuit (7a) ~ 7c) part of the load driving device is unused,
Based on the potential of the clamp terminals (11a to 11c) to which the potential of the control terminal (1b) is input, the clamp state and the path from the control terminal (1b) through the clamp circuits (5a to 5c) A clamp disconnection control circuit (55) for detecting a disconnection state;
The temperature detection circuits (7a to 7c) determine the overheating state of the power element (1a) based on the potential of the temperature detection terminals (14a to 14c) connected to the output terminal (1f) of the temperature sensor (1h). An overheat detection circuit (71) for detecting, a disconnection detection circuit (72) for detecting a disconnection state between the temperature sensor (1h) and the temperature detection terminals (14a to 14c), and the temperature detection terminals (14a to 14c) ) Includes a disconnection detection invalidation circuit (73) for detecting a disconnection invalid state to which the temperature sensor (1h) is not connected, and when the disconnection invalid state is detected, a signal indicating that is provided in the clamp disconnection control circuit Configured to output to (55),
The clamp disconnection control circuit (55) inputs a signal output when the disconnection detection invalidation circuit (73) of the temperature detection circuits (7a to 7c) detects the disconnection invalid state, and the signal is input. Then, it is determined that the clamp circuits (5a to 5c) are not in the disconnection invalid state, not the disconnection state of the path through the clamp circuits (5a to 5c).   The clamp disconnection control circuit (55) includes a control signal (8) for controlling on / off of the gate driver circuit (3) and the gate-off circuit (4), outputs of the temperature detection circuits (7a to 7c), and the clamp Based on the potential of the terminals (11a to 11c), it is determined whether the clamp state, the disconnection state, or the disconnection invalid state, and when the gate-off circuit (4) is turned on by the control signal, The clamp circuit (5a to 5c) is determined to be in the disconnection invalid state when a signal output when the disconnection invalidation state is detected from the disconnection detection invalidation circuit (73) is input. Item 2. The load driving device according to Item 1.   In the temperature detection circuits (7a to 7c), if the potential of the temperature detection terminals (14a to 14c) is outside the voltage range output from the output terminal (1f) of the temperature sensor (1h), the disconnection detection is invalid. 3. The load driving device according to claim 1, wherein the disconnection invalid state is detected by an activating circuit (73), and a signal indicating that is output to the clamp disconnection control circuit (55).   The load driving device according to any one of claims 1 to 3, wherein the clamp disconnection control circuit (55) is provided in the clamp circuits (5a to 5c). The gate driver circuit (3), the gate-off circuit (4), the clamp circuits (5a to 5c) and the temperature detection circuit (7a to 7c) are connected to a control IC (2) that controls the power element (1a). 5. The load driving device according to claim 1, further comprising a clamp disconnection control circuit (55) provided in the control IC (2).   The load driving device according to any one of claims 1 to 5, wherein the clamp disconnection control circuit (55) is configured by CMOS logic. 6. The load driving device according to claim 5 , wherein the control IC (2) is constituted by a semiconductor element circuit in which a bipolar transistor, CMOS and DMOS are combined.

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