Control device

Abstract

To provide a control device which suppresses increase in the voltage of a terminal arranged on the downstream side of a processor in a current path of a current flowing via the processor for executing processing.SOLUTION: In a vehicular control device 11, a first terminal G1 is arranged on the downstream side of a microcomputer 30 in a current path of a current flowing via the microcomputer 30. An anode of a connection diode 34 is connected to a connection node between the microcomputer 30 and the first terminal G1. One end of a connection switch 22 is connected to a cathode of the connection diode 34. A second terminal G2 is connected to the other end of the connection switch 22. A switching circuit 35 switches the connection switch 22 from OFF to ON when the voltage of the first terminal G1 with the potential of the second terminal G2 as the reference potential rises to a value equal to or greater than a threshold.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a control device.

Background Art

[0002] Patent Document 1 discloses a control device that controls power supply from a power source to a load. In this control device, a switch is arranged in the current path of the current flowing from the power source to the load. The switch switches between on and off according to a signal output by an IC (Integrated Circuit). The IC is connected to the positive electrode of the power source and the ground terminal. The ground terminal is connected to the ground. From the positive electrode of the power source, the current flows in the order of the IC, the ground terminal, and the ground. Thereby, power is supplied to the IC.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, when the connection between the ground terminal and the ground is disconnected, the voltage of the ground terminal with the ground potential as the reference potential increases. When the voltage of the ground terminal with the ground potential as the reference potential increases, the voltage applied to the IC decreases. When the voltage drop width is large, there is a possibility that the IC does not operate properly.

[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a control device that suppresses an increase in the voltage of a terminal arranged on the downstream side of a processor in a current path flowing through a processor that executes processing.

Means for Solving the Problems

[0006] A control device according to an aspect of the present disclosure is a control device for a vehicle, including a processor that executes processing, a first terminal disposed on the downstream side of the processor in a current path of a current flowing through the processor, a diode having an anode connected to a connection node between the processor and the first terminal, a connection switch having one end connected to the cathode of the diode, a second terminal connected to the other end of the connection switch, and a switching circuit that switches the connection switch from off to on when a voltage of the first terminal with the potential of the second terminal as a reference potential rises to a value equal to or higher than a threshold value.

Effects of the Invention

[0007] According to the above aspect, in a current path flowing through a processor that executes processing, an increase in the voltage of a terminal disposed on the downstream side of the processor is suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. At least a part of the embodiments described below may be arbitrarily combined.

[0010] (1) A control device according to an aspect of the present disclosure is a control device for a vehicle, including a processor that executes processing, a first terminal disposed downstream of the processor in a current path of a current flowing through the processor, a diode having an anode connected to a connection node between the processor and the first terminal, a connection switch having one end connected to a cathode of the diode, a second terminal connected to the other end of the connection switch, and a switching circuit that switches the connection switch from off to on when a voltage of the first terminal with the potential of the second terminal as a reference potential rises to a value equal to or higher than a threshold value.

[0011] In the above aspect, each of the first terminal and the second terminal is connected to a common conductor. The current flows in the order of the processor, the first terminal, and the conductor, and power is supplied to the processor. For example, when the connection between the first terminal and the conductor is disconnected, the voltage of the first terminal with the potential of the second terminal as a reference potential rises. When the voltage of the first terminal with the potential of the second terminal as a reference potential rises to a value equal to or higher than a threshold value, the switching circuit switches the connection switch to on. When the connection switch is on, the current flows in the order of the processor, the diode, the connection switch, the second terminal, and the conductor.

[0012] In this case, the voltage of the first terminal with the potential of the second terminal as a reference potential is a forward voltage. Therefore, even when the voltage of the first terminal with the potential of the second terminal as a reference potential rises, the voltage of the first terminal with the potential of the second terminal as a reference potential does not exceed the larger voltage of the threshold value and the forward voltage and is suppressed.

[0013] (2) A control device according to an aspect of the present disclosure includes a power supply switch disposed in a power supply path from a DC power supply to a load, and the processor instructs switching of the power supply switch to on or off.

[0014] In the above aspect, the processor controls the power supply from the DC power supply to the load by instructing the switching of the power supply switch to on or off.

[0015] (3) The control device according to one aspect of the present disclosure includes a first substrate on which the processor is disposed, and a second substrate different from the first substrate on which the power supply switch is disposed.

[0016] In the above aspect, each of the processor and the power supply switch is disposed on the first substrate and the second substrate. Therefore, by changing the second substrate, the power supply switch can be changed without changing the processor.

[0017] (4) The control device according to one aspect of the present disclosure includes a second diode having a cathode connected to a connection node between the power supply switch and the load, and a second connection switch connected between the anode of the second diode and the second terminals, and the load has an inductor.

[0018] In the above aspect, while power is being supplied to the load, energy is stored in the inductor of the load. When the second terminal and one end of the load are connected to a conductor, when the second connection switch is on, current flows from one end of the load in the order of the conductor, the second terminal, the second connection switch, the second diode, and the other end of the load. As a result, the energy stored in the inductor is released.

[0019] (5) In the control device according to one aspect of the present disclosure, when the processor instructs the switching of the power supply switch to on, it instructs the switching of the second connection switch to on, and when it instructs the switching of the power supply switch to off, it instructs the switching of the second connection switch to off.

[0020] In the above aspect, when one end of the second terminal and the load are connected to the conductor, when the power supply switch and the second connection switch are on and off respectively, power is supplied from the DC power supply to the load via the power supply switch. Energy is stored in the inductor of the load. When the power supply switch and the second connection switch are switched to off and off respectively, the energy stored in the inductor is released.

[0021] (6) The control device according to one aspect of the present disclosure includes a regulator that steps down the power supply voltage of the DC power supply with the potential of the first terminal as the reference potential to the target voltage and applies the target voltage to the processor. The switching circuit switches the connection switch from off to on in a state where the power supply voltage is equal to or higher than the target voltage.

[0022] In the above aspect, the switching circuit switches the connection switch from off to on before the power supply voltage with the potential of the first terminal as the reference potential drops to a value less than the target voltage. Therefore, even when the voltage of the first terminal with the potential of the second terminal as the reference potential increases, the regulator continues to apply the target voltage to the processor.

[0023] (7) The control device according to one aspect of the present disclosure includes a resistor having one end connected to the second terminal. The connection switch has a control end, and the other end of the resistor is connected to the control end of the connection switch. The connection switch switches from off to on when the voltage of the control end with the potential of the second terminal as the reference potential rises to a value equal to or higher than a predetermined voltage. The switching circuit has a circuit switch having an input end to which current is input and an output end from which current is output. The output end of the circuit switch is connected to the control end of the connection switch, and a circuit voltage is applied to the input end of the circuit switch. The circuit switch switches from off to on when the voltage of the first terminal with the potential of the second terminal as the reference potential rises to a value equal to or higher than the threshold value.

[0024] In the above aspect, when the voltage of the first terminal with the potential of the second terminal as the reference potential rises to a value equal to or higher than the threshold value, the circuit switch switches from off to on. When the circuit switch is on, the current flows in the order of the circuit switch, the resistor, and the second terminal. As a result, a voltage drop occurs across the resistor. Consequently, the voltage of the control terminal with the potential of the second terminal as the reference potential rises to a value equal to or higher than the predetermined voltage, and the connection switch switches from off to on.

[0025] (8) In the control device according to one aspect of the present disclosure, the circuit switch has a second control terminal, and the circuit switch is on when the voltage of the second control terminal with the potential of the input terminal as the reference potential is equal to or lower than a second predetermined voltage. The switching circuit includes a circuit resistor connected between the input terminal and the second control terminal of the circuit switch, and a second circuit switch connected between the second control terminal of the circuit switch and the second terminal. The second circuit switch switches from off to on when the voltage of the first terminal with the potential of the second terminal as the reference potential rises to a value equal to or higher than the threshold value.

[0026] In the above aspect, when the voltage of the first terminal with the potential of the second terminal as the reference potential rises to a value equal to or higher than the threshold value, the second circuit switch switches from off to on. When the second circuit switch is on, the current flows in the order of the circuit resistor, the second circuit switch, and the second terminal, and a voltage drop occurs across the circuit resistor. As a result, the voltage of the second control terminal with the potential of the input terminal as the reference potential drops to a value equal to or lower than the second predetermined voltage, and the circuit switch switches to on.

[0027] (9) The control device according to one aspect of the present disclosure includes a voltage detection circuit that detects the power supply voltage of the DC power supply with the potential of the first terminal as the reference potential. The switching circuit switches the connection switch from off to on when the voltage of the first terminal with the potential of the second terminal as the reference potential rises to a value equal to or higher than the threshold value in a state where the power supply voltage detected by the voltage detection circuit is less than a third predetermined voltage.

[0028] In the above aspect, when the voltage of the first terminal with the potential of the second terminal as the reference potential increases, the power supply voltage with the potential of the first terminal as the reference potential decreases. When the voltage of the first terminal with the potential of the second terminal as the reference potential rises to a value equal to or higher than the threshold value in a state where the power supply voltage with the potential of the first terminal as the reference potential is less than the third predetermined voltage, the connection switch changes from off to on. Therefore, the connection switch changes from off to on when there is a high possibility that the voltage of the first terminal has increased.

[0029] [Details of Embodiments of the Present Disclosure] A specific example of the power supply system according to the embodiment of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, and is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0030] (Embodiment 1) <Configuration of Power Supply System> FIG. 1 is a block diagram showing a main configuration of a power supply system 1 in Embodiment 1. The power supply system 1 is mounted on a vehicle M. The power supply system 1 includes a DC power supply 10, a control device 11, an inductive load 12, and a ground conductor 13. The DC power supply 10 is, for example, a battery. The inductive load 12 has an inductor 12a and is, for example, a motor. The ground conductor 13 is, for example, the body of the vehicle M. Grounding is achieved by connecting to the ground conductor 13.

[0031] The positive electrode of the DC power supply 10 is connected to the control device 11. The control device 11 is further connected to one end of the inductive load 12 and the ground conductor 13. The other end of the inductive load 12 and the negative electrode of the DC power supply 10 are connected to the ground conductor 13.

[0032] The control device 11 has a power supply switch 20 (see FIG. 2). When the power supply switch 20 is switched from off to on, current flows from the positive electrode of the DC power supply 10, through the power supply switch 20, the inductive load 12, and the ground conductor 13 in that order, and power is supplied to the inductive load 12. When power is supplied to the inductive load 12, the inductive load 12 operates. The power supply switch 20 is arranged in the power supply path from the DC power supply 10 to the inductive load 12.

[0033] When the power supply switch 20 is switched from on to off, the power supply from the DC power supply 10 to the inductive load 12 stops. When the power supply to the inductive load 12 stops, the inductive load 12 stops operating. The control device 11 controls the power supply from the DC power supply 10 to the inductive load 12 via the power supply switch 20 by switching the power supply switch 20 on or off.

[0034] <Configuration of the control device 11> FIG. 2 is a circuit diagram of the control device 11. In addition to the power supply switch 20, the control device 11 includes a discharge switch 21, a connection switch 22, power supply resistors 23, 24, discharge resistors 25, 26, connection resistors 27, 28, a regulator 29, a microcomputer (hereinafter referred to as a microcontroller) 30, a drive circuit 31, an inverter 32, a discharge diode 33, a connection diode 34, a switching circuit 35, a first terminal G1, a second terminal G2, a power supply terminal Gb, and a load terminal Gf. The first terminal G1 and the second terminal G2 are connected to the ground conductor 13. The power supply terminal Gb is connected to the positive electrode of the DC power supply 10. The load terminal Gf is connected to one end of the inductive load 12. As described above, the other end of the inductive load 12 is connected to the ground conductor 13.

[0035] The inductive load 12, the first terminal G1, and the second terminal G2 are each connected to three positions on the ground conductor 13. Note that at least two of the inductive load 12, the first terminal G1, and the second terminal G2 may be connected to a common position on the ground conductor 13.

[0036] The power supply switch 20, the discharge switch 21, and the connection switch 22 are each an N-channel type FET (Field Effect Transistor). When the power supply switch 20 is manufactured, a parasitic diode 20a is formed. Each of the cathode and anode of the parasitic diode 20a is connected to the drain and source of the power supply switch 20. A power supply resistor 23 is connected between the gate and source of the power supply switch 20. One end of a power supply resistor 24 is further connected to the gate of the power supply switch 20.

[0037] Similarly, when the discharge switch 21 is manufactured, a parasitic diode 21a is formed. Each of the cathode and anode of the parasitic diode 21a is connected to the drain and source of the discharge switch 21. A discharge resistor 25 is connected between the gate and source of the discharge switch 21. One end of a discharge resistor 26 is further connected to the gate of the discharge switch 21. When the connection switch 22 is manufactured, a parasitic diode 22a is formed. Each of the cathode and anode of the parasitic diode 22a is connected to the drain and source of the connection switch 22. A connection resistor 27 is connected between the gate and source of the connection switch 22. One end of a connection resistor 28 is further connected to the gate of the connection switch 22.

[0038] Each of the drain and source of the power supply switch 20 is connected to a power supply terminal Gb and a load terminal Gf. The drain of the power supply switch 20 is further connected to a regulator 29. The regulator 29 is further connected to a microcomputer 30 and a first terminal G1. Each of the drive circuit 31 and the inverter 32 has an input end and an output end. The microcomputer 30 is further connected to the input ends of the drive circuit 31 and the inverter 32 and the first terminal G1.

[0039] The output terminal of the drive circuit 31 is connected to the other end of the power supply resistor 24. The output terminal of the inverter 32 is connected to the other end of the discharge resistor 26. The anode of the connection diode 34 is connected to the connection node between the microcomputer 30 and the first terminal G1. The cathode of the connection diode 34 is connected to the drain of the connection switch 22. The source of the connection switch 22 is connected to the second terminal G2. The cathode of the discharge diode 33 is connected to the connection node between the power supply switch 20 and the load terminal Gf. The connection node between the power supply switch 20 and the load terminal Gf is the connection node between the power supply switch 20 and the inductive load 12. Therefore, the discharge diode 33 functions as the second diode.

[0040] The anode of the discharge diode 33 is connected to the source of the discharge switch 21. The drain of the discharge switch 21 is connected to the second terminal G2. The switching circuit 35 is connected to the other end of the connection resistor 28, the first terminal G1, and the second terminal G2.

[0041] For each of the power supply switch 20, the discharge switch 21, and the connection switch 22, the voltage of the gate with the source potential as the reference potential is described as the gate voltage. When the gate voltage of each of the power supply switch 20, the discharge switch 21, and the connection switch 22 rises to a value equal to or higher than a certain voltage, it switches from off to on. The gate of the connection switch 22 functions as a control terminal. The certain voltage of the connection switch 22 corresponds to a predetermined voltage. When each of the power supply switch 20, the discharge switch 21, and the connection switch 22 is on, the resistance value between the drain and the source is sufficiently small. Therefore, current can flow through the drain and the source. The certain voltage is a positive value.

[0042] When the gate voltage of each of the power supply switch 20, the discharge switch 21, and the connection switch 22 drops to a value less than the certain voltage, it switches to off. When each of the power supply switch 20, the discharge switch 21, and the connection switch 22 is off, the resistance value between the drain and the source is sufficiently large. Therefore, no current flows through the drain and the source.

[0043] The drive circuit 31 raises the voltage of the gate with respect to the power supply switch 20, taking the potential of the second terminal G2 as the reference potential. As a result, the gate voltage of the power supply switch 20 rises to a value equal to or higher than a certain voltage, and the power supply switch 20 switches to the on state. The drive circuit 31 lowers the voltage of the gate with respect to the power supply switch 20, taking the potential of the second terminal G2 as the reference potential. As a result, the gate voltage of the power supply switch 20 drops to a value less than the certain voltage, and the power supply switch 20 switches to the off state. As described above, the drive circuit 31 switches the power supply switch 20 between on and off.

[0044] The inverter 32 outputs a low-level voltage and a high-level voltage with respect to the potential of the second terminal G2 from the output terminal. The low-level voltage output by the inverter 32 is, for example, 0V. The high-level voltage output by the inverter 32 is, for example, the voltage between both ends of the DC power supply 10.

[0045] When the inverter 32 switches the output voltage from the low-level voltage to the high-level voltage, with respect to the discharge switch 21, the voltage of the gate with respect to the potential of the second terminal G2 rises. As a result, the gate voltage of the discharge switch 21 rises to a value equal to or higher than a certain voltage, and the discharge switch 21 switches to the on state. When the inverter 32 switches the output voltage from the high-level voltage to the low-level voltage, with respect to the discharge switch 21, the voltage of the gate with respect to the potential of the second terminal G2 drops. As a result, the gate voltage of the discharge switch 21 drops to a value less than the certain voltage, and the discharge switch 21 switches to the off state. As described above, the inverter 32 switches the discharge switch 21 between on and off by switching the output voltage between the low-level voltage and the high-level voltage.

[0046] The current flows from the positive electrode of the DC power supply 10, through the power supply terminal Gb, the regulator 29, the first terminal G1, the ground conductor 13, and to the negative electrode of the DC power supply 10 in this order, and power is supplied to the regulator 29. The voltage of the positive electrode of the DC power supply 10 is referred to as the power supply voltage. The regulator 29 steps down the power supply voltage with the potential of the first terminal G1 as the reference potential to a constant target voltage, and applies the target voltage obtained by the step-down to the microcomputer 30. The reference potential of the target voltage is the potential of the first terminal G1. By applying the target voltage, power is supplied to the microcomputer 30.

[0047] While power is being supplied to the microcomputer 30, the current flows from the positive electrode of the DC power supply 10, through the power supply terminal Gb, the regulator 29, the microcomputer 30, the first terminal G1, the ground conductor 13, and to the negative electrode of the DC power supply 10 in the order indicated by the arrow. Therefore, the first terminal G1 is arranged on the downstream side of the microcomputer 30 in the current path flowing through the microcomputer 30.

[0048] The microcomputer 30 outputs a high-level voltage or a low-level voltage to the input ends of the drive circuit 31 and the inverter 32. The reference potential of the high-level voltage and the low-level voltage output by the microcomputer 30 is the potential of the first terminal G1. The high-level voltage is, for example, the target voltage output from the regulator 29. The low-level voltage is, for example, 0V. When the microcomputer 30 switches the output voltage from the low-level voltage to the high-level voltage, the drive circuit 31 switches the power supply switch 20 from off to on, and the inverter 32 switches the output voltage from the high-level voltage to the low-level voltage. As a result, the discharge switch 21 switches from on to off.

[0049] When the microcomputer 30 switches the output voltage from the high-level voltage to the low-level voltage, the drive circuit 31 switches the power supply switch 20 from on to off, and the inverter 32 switches the output voltage from the low-level voltage to the high-level voltage. As a result, the discharge switch 21 switches from off to on.

[0050] As described above, the microcomputer 30 instructs the drive circuit 31 to switch the power supply switch 20 on and instructs the inverter 32 to switch the discharge switch 21 off by switching the output voltage to the high-level voltage. Further, the microcomputer 30 instructs the drive circuit 31 to switch the power supply switch 20 off and instructs the inverter 32 to switch the discharge switch 21 on by switching the output voltage to the low-level voltage.

[0051] The microcomputer 30 executes a power supply control process for controlling the power supply to the inductive load 12. The microcomputer 30 functions as a processor. The microcomputer 30 controls the power supply from the DC power supply 10 to the inductive load 12 by instructing the switching of the power supply switch 20 on or off.

[0052] FIG. 3 is a timing chart for explaining the power supply control process. FIG. 3 shows the transition of the output voltage of the microcomputer 30 and the transition of the states of the power supply switch 20 and the discharge switch 21. Time is shown on the horizontal axis of each transition. In FIG. 3, the high-level voltage and the low-level voltage are indicated by H and L, respectively.

[0053] When the microcomputer 30 switches the output voltage from the low-level voltage to the high-level voltage, the drive circuit 31 switches the power supply switch 20 from off to on, and the inverter 32 switches the discharge switch 21 from on to off. As a result, the current flows from the positive electrode of the DC power supply 10 in the order of the power supply switch 20, the load terminal Gf, the inductive load 12, the ground conductor 13, and the negative electrode of the DC power supply 10. Thereby, power is supplied to the inductive load 12, and the inductive load 12 operates. While power is being supplied to the inductive load 12, the current continues to flow through the inductor 12a, and energy is stored in the inductor 12a.

[0054] The anode of the discharge diode 33 is connected to the anode of the parasitic diode 21a of the discharge switch 21. Therefore, when the discharge switch 21 is off, no current flows through the discharge diode 33.

[0055] When the microcomputer 30 switches the output voltage from the high-level voltage to the low-level voltage, the drive circuit 31 switches the power supply switch 20 from on to off, and the inverter 32 switches the discharge switch 21 from off to on. When the power supply switch 20 is switched off, the flow of current through the inductive load 12 stops. As a result, the power supply to the inductive load 12 stops, and the inductive load 12 stops operating.

[0056] When the power supply switch 20 is switched off, the discharge switch 21 is switched on. When the discharge switch 21 is on, current flows from one end of the inductive load 12 on the ground conductor 13 side, through the ground conductor 13, the second terminal G2, the discharge switch 21, the discharge diode 33, the load terminal Gf, and the other end of the inductive load 12 in that order. As a result, the energy of the inductor 12a is released. As a result, a large drop in the voltage of the load terminal Gf with the potential of the ground conductor 13 as the reference potential is prevented.

[0057] <Configuration of the switching circuit 35> FIG. 4 is a circuit diagram of the switching circuit 35. The switching circuit 35 includes a first circuit switch 41, a second circuit switch 42, first circuit resistors 43 and 44, and second circuit resistors 45 and 46. The first circuit switch 41 is a PNP bipolar transistor. The second circuit switch 42 is an NPN bipolar transistor. A constant circuit voltage Vc is applied to the emitter of the first circuit switch 41. The first example of the circuit voltage Vc is the voltage across the DC power supply 10. The second example of the circuit voltage Vc is the target voltage output by the regulator 29.

[0058] The collector of the first circuit switch 41 is connected to the other end of the connection resistor 28. Therefore, the collector of the first circuit switch 41 is connected to the gate of the connection switch 22 via the connection resistor 28. A first circuit resistor 43 is connected between the emitter and the base of the first circuit switch 41. A first circuit resistor 44 is connected between the base of the first circuit switch 41 and the collector of the second circuit switch 42. The emitter of the second circuit switch 42 is connected to the second terminal G2. Therefore, the second circuit switch 42 is connected between the base of the first circuit switch 41 and the second terminal G2. A second circuit resistor 45 is connected between the base and the emitter of the second circuit switch 42. The base of the second circuit switch 42 is further connected to one end of a second circuit resistor 46. The other end of the second circuit resistor 46 is connected to the first terminal G1.

[0059] For each of the first circuit switch 41 and the second circuit switch 42, the voltage of the base with the potential of the emitter as the reference potential is referred to as the base voltage. For the first circuit switch 41, when the base voltage is equal to or lower than a certain first voltage, the first circuit switch 41 is on. The first voltage is a negative value and corresponds to a second predetermined voltage. When the first circuit switch 41 is on, the resistance value between the emitter and the collector is sufficiently small. Therefore, current can flow in the order of the emitter and the collector. The emitter of the first circuit switch 41 functions as an input terminal to which current is input. The collector of the first circuit switch 41 functions as an output terminal from which current is output. The base of the first circuit switch 41 functions as a second control terminal.

[0060] For the first circuit switch 41, when the base voltage exceeds the first voltage, the first circuit switch 41 is off. When the first circuit switch 41 is off, the resistance value between the emitter and the collector is sufficiently large. Therefore, current does not flow through the emitter and the collector.

[0061] Regarding the second circuit switch 42, when the base voltage is equal to or higher than a second voltage that is constant, the second circuit switch 42 is on. The second voltage is a positive value. When the second circuit switch 42 is on, the resistance value between the collector and the emitter is sufficiently small. Therefore, current can flow in the order of the collector and the emitter. The collector of the second circuit switch 42 functions as an input terminal to which current is input. The emitter of the second circuit switch 42 functions as an output terminal from which current is output.

[0062] Regarding the second circuit switch 42, when the base voltage is less than the second voltage, the second circuit switch 42 is off. When the second circuit switch 42 is off, the resistance value between the emitter and the collector is sufficiently large. Therefore, current does not flow through the emitter and the collector.

[0063] Hereinafter, the voltage of the first terminal G1 with respect to the reference potential of the potential of the second terminal G2 is referred to as the terminal voltage. When the first terminal G1 is connected to the ground conductor 13, the terminal voltage is 0V. When the terminal voltage is 0V, current does not flow through the second circuit resistors 45, 46. Therefore, the base voltage of the second circuit switch 42 is 0V and less than the positive second voltage. Therefore, the second circuit switch 42 is off.

[0064] When the second circuit switch 42 is off, current does not flow through the first circuit resistors 43, 44. Therefore, the base voltage of the first circuit switch 41 is 0V and exceeds the negative first voltage. Therefore, the first circuit switch 41 is off. When the first circuit switch 41 is off, current does not flow through the connection resistors 27, 28. Therefore, the gate voltage of the connection switch 22 is 0V and less than a positive constant voltage. Therefore, the connection switch 22 is off.

[0065] As described above, when the second circuit switch 42 is off, the first circuit switch 41 is off. When the first circuit switch 41 is off, the connection switch 22 is off.

[0066] When the connection between the first terminal G1 and the ground conductor 13 is disconnected, the current flowing through the first terminal G1 stops, and the terminal voltage rises. Also, when external noise enters the first terminal G1, the terminal voltage may rise. When the terminal voltage exceeds 0V, the current flows in the order of the second circuit resistors 46, 45, and the second terminal G2, and a voltage drop occurs in the second circuit resistor 45. As a result, the base voltage of the second circuit switch 42 rises. When the terminal voltage is the voltage threshold value, the base voltage of the second circuit switch 42 is the second voltage.

[0067] When the terminal voltage rises to a value equal to or higher than the voltage threshold value, the base voltage of the second circuit switch 42 rises to a value equal to or higher than the second voltage. As a result, the second circuit switch 42 switches to on. When the second circuit switch 42 is on, the current flows in the order of the first circuit resistors 43, 44, the second circuit switch 42, the second terminal G2, and the ground conductor 13. Thereby, a voltage drop occurs in the first circuit resistor 43. Due to this voltage drop, the base voltage of the first circuit switch 41 drops to a value equal to or lower than the first voltage. Therefore, when the second circuit switch 42 switches from off to on, the first circuit switch 41 also switches from off to on.

[0068] When the first circuit switch 41 is on, the current flows in the order of the first circuit switch 41, the connection resistors 28, 27, the second terminal G2, and the ground conductor 13. Thereby, a voltage drop occurs in the connection resistor 27. Due to this voltage drop, the gate voltage of the connection switch 22 rises to a value equal to or higher than a certain voltage. Therefore, when the first circuit switch 41 switches from off to on, the connection switch 22 also switches from off to on.

[0069] As described above, when the second circuit switch 42 is on, the first circuit switch 41 is on. When the first circuit switch 41 is on, the connection switch 22 is on.

[0070] FIG. 5 is a timing chart for explaining the operation of the switching circuit 35. FIG. 5 shows the transitions of the power supply voltage and the terminal voltage. The reference potential of the power supply voltage shown in FIG. 5 is the potential of the first terminal G1. As described above, the terminal voltage is the voltage of the first terminal G1 with the potential of the second terminal G2 as the reference potential. FIG. 5 further shows the transitions of the states of the second circuit switch 42, the first circuit switch 41, and the connection switch 22. For the five transitions shown in FIG. 5, time is shown on the horizontal axis. The high-level voltage and the low-level voltage are indicated by H and L, respectively.

[0071] The regulator 29 steps down the power supply voltage with the potential of the first terminal G1 as the reference potential to the target voltage. Vs indicates the target voltage. Vth indicates the voltage threshold. Vd is the voltage across both ends of the connection diode 34 when the current flows through the anode and the cathode of the connection diode 34 in this order. Vd is the so-called forward voltage of the connection diode 34.

[0072] Hereinafter, the operation of the switching circuit 35 when no disturbance noise is generated will be described. When the first terminal G1 is connected to the ground conductor 13, the terminal voltage is 0V. Therefore, the power supply voltage with the potential of the first terminal G1 as the reference potential is the voltage across both ends of the DC power supply 10 and is higher than the target voltage Vs. When the terminal voltage is 0V, as described above, the second circuit switch 42 is off. When the second circuit switch 42 is off, the first circuit switch 41 and the connection switch 22 are also off.

[0073] When the connection between the first terminal G1 and the ground conductor 13 is disconnected, the flow of current through the first terminal G1 stops and the terminal voltage rises. When the terminal voltage rises, the power supply voltage with the potential of the first terminal G1 as the reference potential decreases. When the terminal voltage rises to a value equal to or higher than the voltage threshold Vth, the second circuit switch 42 switches from off to on. As a result, the first circuit switch 41 and the connection switch 22 sequentially switch from off to on.

[0074] When the connection switch 22 is on, current flows from the positive electrode of the DC power supply 10 in the order of the power supply terminal Gb, the regulator 29, the connection diode 34, the connection switch 22, the second terminal G2, and the negative electrode of the DC power supply 10. Thereby, power is supplied to the regulator 29. The regulator 29 steps down the power supply voltage with the potential of the first terminal G1 as the reference potential to the target voltage Vs, and applies the target voltage Vs with the potential of the first terminal G1 as the reference potential to the microcomputer 30. In this case, current flows from the positive electrode of the DC power supply 10 in the order of the power supply terminal Gb, the regulator 29, the microcomputer 30, the connection diode 34, the connection switch 22, the second terminal G2, and the negative electrode of the DC power supply 10. Power is supplied to the microcomputer 30.

[0075] Before the power supply voltage with the potential of the first terminal G1 as the reference potential drops to a value less than the target voltage Vs, the second circuit switch 42 switches from off to on. Therefore, the switching circuit 35 switches the connection switch 22 from off to on in a state where the power supply voltage with the potential of the first terminal G1 as the reference potential is equal to or higher than the target voltage Vs. For this reason, even when the terminal voltage increases due to disconnection between the first terminal G1 and the ground conductor 13, the regulator 29 continues to apply the target voltage Vs to the microcomputer 30.

[0076] When the connection switch 22 is on, the terminal voltage drops to the forward voltage Vd of the connection diode 34. When the terminal voltage drops to the forward voltage Vd, the power supply voltage with the potential of the first terminal G1 as the reference potential increases. The forward voltage Vd is less than the voltage threshold Vth. Therefore, when the terminal voltage drops to the forward voltage Vd, the second circuit switch 42 switches from on to off. Thereby, the first circuit switch 41 and the connection switch 22 sequentially switch from on to off.

[0077] When the terminal voltage drops to the forward voltage Vd, the connection switch 22 switches off while the connection between the first terminal G1 and the ground conductor 13 is disconnected. As a result, the terminal voltage rises again. When the terminal voltage rises to a value equal to or higher than the voltage threshold Vth, the terminal voltage drops to the forward voltage Vd again. Therefore, when the connection between the first terminal G1 and the ground conductor 13 is disconnected, the terminal voltage fluctuates between the forward voltage Vd and the voltage threshold Vth. As a result, the target voltage Vs continues to be applied to the microcomputer 30.

[0078] Even when the first terminal G1 is connected to the ground conductor 13, when the terminal voltage rises to a value equal to or higher than the voltage threshold due to external noise, the second circuit switch 42, the first circuit switch 41, and the connection switch 22 are sequentially switched from off to on. As a result, the terminal voltage drops to the forward voltage Vd. Therefore, even when external noise enters the first terminal G1, the terminal voltage does not exceed the voltage threshold Vth.

[0079] As described above, when the terminal voltage rises to a value equal to or higher than the voltage threshold Vth, the second circuit switch 42 switches from off to on. When the second circuit switch 42 switches from off to on, the gate voltage of the first circuit switch 41 drops to a value equal to or lower than the negative first voltage, and the first circuit switch 41 switches from off to on. When the first circuit switch 41 switches from off to on, the switching circuit 35 switches the connection switch 22 from off to on.

[0080] Note that when the forward voltage Vd of the connection diode 34 is equal to or higher than the voltage threshold Vth, after the second circuit switch 42 switches from off to on, the terminal voltage is maintained at the forward voltage Vd of the connection diode 34. The second circuit switch 42, the first circuit switch 41, and the connection switch 22 are fixed in the on state, and the switching of the second circuit switch 42 between on and off is not repeated alternately.

[0081] As described above, even when the connection of the first terminal G1 is disconnected or the terminal voltage increases due to external noise, the terminal voltage does not exceed the larger voltage of the voltage threshold Vth and the forward voltage Vd and is suppressed.

[0082] <Arrangement of Components of Control Device 11> FIG. 6 is an explanatory diagram of the arrangement of components of the control device 11. The control device 11 has a first substrate B1 and a second substrate B2. The second substrate B2 is different from the first substrate B1. A regulator 29 and a microcomputer 30 are arranged on the first substrate B1. A power supply switch 20, a discharge switch 21, a connection switch 22, a drive circuit 31, and a switching circuit 35 are arranged on the second substrate B2. The arrangement of the switching circuit 35 means the arrangement of a first circuit switch 41, a second circuit switch 42, first circuit resistors 43 and 44, and second circuit resistors 45 and 46 included in the switching circuit 35.

[0083] In FIG. 6, the description of the power supply resistors 23 and 24, the discharge resistors 25 and 26, the connection resistors 27 and 28, the inverter 32, the discharge diode 33, the connection diode 34, the first terminal G1, the second terminal G2, the power supply terminal Gb, and the load terminal Gf is omitted. The first terminal G1 is arranged on the first substrate B1. The power supply resistors 23 and 24, the discharge resistors 25 and 26, the connection resistors 27 and 28, the inverter 32, the discharge diode 33, the connection diode 34, the second terminal G2, the power supply terminal Gb, and the load terminal Gf are arranged on the second substrate B2. The first substrate B1 and the second substrate B2 are connected by a connection line.

[0084] As described above, when circuit components are arranged on each of the first substrate B1 and the second substrate B2, for example, when a failure occurs in the power supply switch 20 arranged on the second substrate B2, the power supply switch 20 can be changed by changing the second substrate B2 without changing the regulator 29 and the microcomputer 30.

[0085] Note that the substrate on which the connection switch 22, connection resistors 27 and 28, connection diode 34, and switching circuit 35 are arranged is not limited to the second substrate B2, and may be arranged on the first substrate B1. The number of substrates on which the circuit components of the control device 11 are arranged is not limited to 2, and may be 1 or 3 or more. The circuit components include the power supply switch 20, discharge switch 21, connection switch 22, regulator 29, microcomputer 30, drive circuit 31, inverter 32, discharge diode 33, connection diode 34, switching circuit 35, etc. shown in FIG. 2.

[0086] (Embodiment 2) In Embodiment 1, the microcomputer 30 may monitor the power supply voltage with the potential of the first terminal G1 as the reference potential. Hereinafter, for Embodiment 2, the differences from Embodiment 1 will be described. For other configurations except for the configurations described later, they are common to Embodiment 1. Therefore, the same reference numerals as those in Embodiment 1 are given to the components common to Embodiment 1, and the description of those components is omitted.

[0087] <Configuration of Control Device 11> FIG. 7 is a circuit diagram of the control device 11 in Embodiment 2. The control device 11 in Embodiment 2 has the same components as those of the control device 11 in Embodiment 1. The control device 11 further includes a voltage detection circuit 36. The voltage detection circuit 36 includes voltage dividing resistors 50 and 51. One end of the voltage dividing resistor 50 is connected to the drain of the power supply switch 20. The other end of the voltage dividing resistor 50 is connected to one end of the voltage dividing resistor 51. The other end of the voltage dividing resistor 51 is connected to the first terminal G1. The connection node between the voltage dividing resistors 50 and 51 is connected to the microcomputer 30.

[0088] The voltage dividing resistors 50 and 51 divide the power supply voltage of the DC power supply 10 with the potential of the first terminal G1 as the reference potential. The divided voltage obtained by the voltage dividing resistors 50 and 51 dividing the power supply voltage is the voltage across both ends of the voltage dividing resistor 51 and is proportional to the power supply voltage with the potential of the first terminal G1 as the reference potential. The divided voltage is power supply voltage information indicating the power supply voltage. As described above, the voltage detection circuit 36 detects the power supply voltage of the DC power supply 10 with the potential of the first terminal G1 as the reference potential and notifies the detected power supply voltage to the microcomputer 30.

[0089] <Configuration of the switching circuit 35> FIG. 8 is a circuit diagram of the switching circuit 35. The switching circuit 35 in the second embodiment has the same components as the switching circuit 35 in the first embodiment. The switching circuit 35 in the second embodiment further includes an AND circuit 47 and a third circuit resistor 48. The AND circuit 47 has two input terminals and one output terminal. The third circuit resistor 48 is connected between the collector of the first circuit switch 41 and the second terminal G2.

[0090] One input terminal of the AND circuit 47 is connected to the microcomputer 30. The other input terminal of the AND circuit 47 is connected to the connection node between the first circuit switch 41 and the third circuit resistor 48. As described in the description of the first embodiment, one end of the connection resistor 28 is connected to the gate of the connection switch 22. The output terminal of the AND circuit 47 is connected to the other end of the connection resistor 28.

[0091] When the power supply voltage detected by the voltage detection circuit 36 is equal to or higher than the set voltage, the microcomputer 30 outputs a low-level voltage to the input terminal of the AND circuit 47. The set voltage is a constant value and is set in advance. The reference potential of the low-level voltage input from the microcomputer 30 to the AND circuit 47 is the potential of the first terminal G1. The low-level voltage is, for example, 0V. When the power supply voltage detected by the voltage detection circuit 36 is less than the set voltage, the microcomputer 30 outputs a high-level voltage to the input terminal of the AND circuit 47. The reference potential of the high-level voltage input from the microcomputer 30 to the AND circuit 47 is also the potential of the first terminal G1. The high-level voltage is, for example, the target voltage output by the regulator 29.

[0092] The voltage across both ends of the third circuit resistor 48 is input to the AND circuit 47. Hereinafter, the voltage across both ends of the third circuit resistor 48 is referred to as the resistor voltage. In the AND circuit 47, a second voltage threshold is set. The second voltage threshold exceeds 0 V and is equal to or less than the circuit voltage Vc.

[0093] When the input voltage input from the microcomputer 30 to the AND circuit 47 is a low-level voltage or the resistor voltage is less than the second voltage threshold, the AND circuit 47 outputs a low-level voltage from the output terminal. The reference potential of the low-level voltage output by the AND circuit 47 is the potential of the second terminal G2. The low-level voltage is, for example, 0 V. When the output voltage of the AND circuit 47 is a low-level voltage, no current flows through the connection resistors 27 and 28. For this reason, the gate voltage of the connection switch 22 is 0 V and less than a positive constant voltage. Therefore, the connection switch 22 is off.

[0094] When the input voltage input from the microcomputer 30 to the AND circuit 47 is a high-level voltage and the resistor voltage is equal to or greater than the second voltage threshold, the AND circuit 47 outputs a high-level voltage from the output terminal. The reference potential of the high-level voltage output by the AND circuit 47 is the potential of the second terminal G2. Here, the first example of the high-level voltage is the voltage across both ends of the DC power supply 10. The second example of the high-level voltage is the target voltage output by the regulator 29.

[0095] When the AND circuit 47 is outputting a high-level voltage, current flows in the order of the connection resistors 28, 27, the second terminal G2, and the ground conductor 13. As a result, a voltage drop occurs in the connection resistor 27. Due to this voltage drop, the gate voltage of the connection switch 22 rises to a value equal to or greater than a constant voltage. Therefore, when the AND circuit 47 is outputting a high-level voltage, the connection switch 22 is on.

[0096] FIG. 9 is a timing chart for explaining the operation of the switching circuit 35. FIG. 9 shows the transitions of the power supply voltage, the terminal voltage, and the input voltage of the AND circuit 47. The reference potential of the power supply voltage shown in FIG. 9 is the potential of the first terminal G1. As described in the description of Embodiment 1, the terminal voltage is the voltage of the first terminal G1 with the potential of the second terminal G2 as the reference potential. FIG. 9 further shows the transitions of the states of the first circuit switch 41, the second circuit switch 42, and the connection switch 22. For the five transitions shown in FIG. 9, time is shown on the horizontal axis. The high-level voltage and the low-level voltage are indicated by H and L, respectively.

[0097] Similar to FIG. 5, Vs, Vth, and Vd are the target voltage, the voltage threshold, and the forward voltage of the connection diode 34, respectively. Vr is the set voltage.

[0098] Hereinafter, the operation of the switching circuit 35 when no disturbance noise is generated and the voltage threshold exceeds the forward voltage Vd of the connection diode 34 will be described. When the first terminal G1 is connected to the ground conductor 13, the terminal voltage is 0V. Therefore, the power supply voltage with the potential of the first terminal G1 as the reference potential is the voltage between both ends of the DC power supply 10 and is higher than the set voltage Vr. The target voltage Vs is higher than the set voltage Vr. Therefore, the input voltage input from the microcomputer 30 to the AND circuit 47 is a low-level voltage.

[0099] When the terminal voltage is 0V, as described in the description of Embodiment 1, the first circuit switch 41, the second circuit switch 42, and the connection switch 22 are off. Therefore, no current flows through the third circuit resistor 48, so the resistor voltage is 0V and is less than the second voltage threshold. Therefore, the output voltage of the AND circuit 47 is a low-level voltage, and the connection switch 22 is off.

[0100] When the connection between the first terminal G1 and the ground conductor 13 is disconnected, the current flowing through the first terminal G1 stops, and the terminal voltage rises. When the terminal voltage rises, the power supply voltage with the potential of the first terminal G1 as the reference potential decreases. When the power supply voltage with the potential of the first terminal G1 as the reference potential drops below the set voltage Vr, the input voltage input from the microcomputer 30 to the AND circuit 47 switches from a low-level voltage to a high-level voltage.

[0101] When the terminal voltage rises to a value equal to or higher than the voltage threshold Vth while the input voltage of the AND circuit 47 is a high-level voltage, the second circuit switch 42 switches from off to on. As a result, the first circuit switch 41 switches from off to on. When the first circuit switch 41 is on, the current flows in the order of the first circuit switch 41, the third circuit resistor 48, the second terminal G2, and the ground conductor 13. As a result, the resistor voltage rises from 0V to the circuit voltage Vc. Since the circuit voltage Vc is equal to or higher than the second voltage threshold, the AND circuit 47 switches the output voltage from a low-level voltage to a high-level voltage. As a result, the connection switch 22 switches from off to on.

[0102] As described in the description of Embodiment 1, when the connection switch 22 is on, the terminal voltage drops to the forward voltage Vd of the connection diode 34. When the terminal voltage drops to the forward voltage Vd, the second circuit switch 42 switches from on to off. As a result, the first circuit switch 41 switches from on to off, and the resistor voltage drops from the circuit voltage Vc to 0V. As a result, the AND circuit 47 switches the output voltage from a high-level voltage to a low-level voltage, and the connection switch 22 switches from on to off. As described in the description of Embodiment 1, when the terminal voltage drops to the forward voltage Vd, the power supply voltage with the potential of the first terminal G1 as the reference potential rises. As a result, the power supply voltage with the potential of the first terminal G1 as the reference potential does not rise to a value equal to or higher than the set voltage Vr.

[0103] Since the connection switch 22 switches off when the connection between the first terminal G1 and the ground conductor 13 is disconnected, the terminal voltage rises again. When the terminal voltage rises to a value equal to or higher than the voltage threshold Vth in a state where the power supply voltage with the potential of the first terminal G1 as the reference potential is lower than the set voltage Vr, the terminal voltage drops again to the forward voltage Vd. Therefore, when the connection between the first terminal G1 and the ground conductor 13 is disconnected, the terminal voltage fluctuates between the forward voltage Vd and the voltage threshold Vth. As a result, the target voltage Vs continues to be applied to the microcomputer 30.

[0104] Even when the first terminal G1 is connected to the ground conductor 13, if the terminal voltage rises to a value equal to or higher than the voltage threshold due to external disturbance noise and the power supply voltage with the potential of the first terminal G1 as the reference potential drops to a value lower than the set voltage Vr, the connection switch 22 switches from off to on. As a result, the terminal voltage drops to the forward voltage Vd. Therefore, even when external disturbance noise enters the first terminal G1, the terminal voltage does not exceed the voltage threshold Vth.

[0105] As described above, when the terminal voltage rises to a value equal to or higher than the voltage threshold Vth in a state where the power supply voltage detected by the voltage detection circuit 36 is lower than the set voltage Vr, the switching circuit 35 switches the connection switch from off to on. Therefore, the connection switch 22 switches from off to on when there is a high possibility that the terminal voltage has risen. The set voltage Vr corresponds to a third predetermined voltage.

[0106] Note that the set voltage Vr only needs to exceed the power supply voltage when the terminal voltage is the voltage threshold Vth. Therefore, the set voltage Vr may be equal to or lower than the power supply voltage when the terminal voltage is the forward voltage Vd of the connection diode 34. Also in this configuration, each of the second circuit switch 42, the first circuit switch 41, and the connection switch 22 repeatedly turns on and off alternately.

[0107] Assume that when the terminal voltage is the forward voltage Vd of the connection diode 34, the power supply voltage is equal to or higher than the set voltage Vr, and the forward voltage Vd of the connection diode 34 is equal to or higher than the voltage threshold Vth. In this case, after the second circuit switch 42 is switched from off to on, the terminal voltage is maintained at the forward voltage Vd of the connection diode 34. The second circuit switch 42, the first circuit switch 41, and the connection switch 22 are fixed to on, and the switching of the second circuit switch 42 between on and off is not repeatedly alternated.

[0108] The control device 11 in Embodiment 2 exhibits the same effects as those of the control device 11 in Embodiment 1, except for the effect obtained by connecting the collector of the first circuit switch 41 to the connection resistor 28.

[0109] <Modification Example> Regarding the switching circuit 35 in Embodiments 1 and 2, the first circuit switch 41 is not limited to a PNP-type bipolar transistor, and may be, for example, a P-channel type FET. The second circuit switch 42 is not limited to an NPN-type bipolar transistor, and may be an N-channel type FET or an IGBT (Insulated Gate Bipolar Transistor). The switching circuit 35 may have any configuration as long as it switches the connection switch 22 from off to on when the terminal voltage rises to a value equal to or higher than the voltage threshold. Therefore, the configuration of the switching circuit 35 is not limited to the configuration using the first circuit switch 41 and the second circuit switch 42.

[0110] In Embodiments 1 and 2, each of the power supply switch 20 and the connection switch 22 is not limited to an N-channel type FET, and may be a P-channel type FET, a bipolar transistor, or the like. When the connection switch 22 is a P-channel type FET, the configuration of the switching circuit 35 is different from the configuration using the first circuit switch 41 and the second circuit switch 42. The discharge switch 21 is not limited to an N-channel type FET, and may be, for example, an NPN-type bipolar transistor.

[0111] In Embodiments 1 and 2, the load to which the DC power supply 10 supplies power is not limited to the inductive load 12, and may be a load that does not include the inductor 12a. In this case, in the control device 11, it is not necessary to arrange the discharge switch 21, the discharge resistors 25 and 26, the inverter 32, and the discharge diode 33. In the control device 11, there is no direct connection between the load terminal Gf and the second terminal G2.

[0112] In Embodiments 1 and 2, the control device 11 is not limited to a device that controls power supply. The control device 11 may be any device that performs control. In this case, the microcomputer 30 executes a control process different from the process of controlling power supply. This process is, for example, a process of transmitting a control signal related to the control of the vehicle M. When the microcomputer 30 executes a control process different from the process of controlling power supply, in the control device 11, the power supply switch 20, the discharge switch 21, the power supply resistors 23 and 24, the discharge resistors 25 and 26, the drive circuit 31, and the inverter 32 are not arranged.

[0113] The disclosed Embodiments 1 and 2 should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Description of Reference Numerals

[0114] 1 Power supply system 10 DC power supply 11 Control device 12 Inductive load 12a Inductor 13 Ground conductor 20 Power supply switch 20a, 21a, 22a Parasitic diodes 21 Discharge switch 22 Connection switch 23, 24 Power supply resistors 25, 26 Discharge resistors 27, 28 Connection resistors 29 Regulator 30 Microcontroller (Processor) 31 Drive Circuit 32 Inverter 33 Discharge Diode (Second Diode) 34 Connection Diode 35 Switching Circuit 36 Voltage Detection Circuit 41 First Circuit Switch 42 Second Circuit Switch 43, 44 First Circuit Resistor 45, 46 Second Circuit Resistor 47 AND Circuit 48 Third Circuit Resistor 50, 51 Voltage Divider Resistors B1 First Substrate B2 Second Substrate G1 First Terminal G2 Second Terminal Gb Power Supply Terminal Gf Load Terminal M Vehicle

Claims

1. A control device for a vehicle, comprising: a processor that executes processing; a first terminal disposed downstream of the processor in a current path of a current flowing through the processor; a diode having an anode connected to a connection node between the processor and the first terminal; a connection switch having one end connected to the cathode of the diode; a second terminal connected to the other end of the connection switch; a switching circuit that switches the connection switch from off to on when a voltage of the first terminal with respect to the potential of the second terminal rises to a value equal to or higher than a threshold; a power supply switch disposed in a power supply path from a DC power supply to a load having an inductor; a second diode having a cathode connected to a connection node between the power supply switch and the load; a second connection switch connected between the anode of the second diode and the second terminal; a resistor having one end connected to the second terminal; and comprising: the first terminal and the second terminal are the ground of the processor; the processor is configured to instruct switching of the power supply switch to on or off; the connection switch has a control terminal; the other end of the resistor is connected to the control terminal of the connection switch; the connection switch switches from off to on when a voltage of the control terminal with respect to the potential of the second terminal rises to a value equal to or higher than a predetermined voltage; the switching circuit has a circuit switch having an input terminal to which a current is input and an output terminal from which a current is output; the output terminal of the circuit switch is connected to the control terminal of the connection switch; a circuit voltage is applied to the input terminal of the circuit switch; the circuit switch switches from off to on when a voltage of the first terminal with respect to the potential of the second terminal rises to a value equal to or higher than the threshold; a control device.

2. a first substrate on which the processor is disposed; a second substrate different from the first substrate and on which the power supply switch is disposed; The control device according to claim 1, comprising:

3. The processor is configured to: instruct switching of the second connection switch to off when instructing switching of the power supply switch to on; instruct switching of the second connection switch to on when instructing switching of the power supply switch to off. The control device according to claim 1 or claim 2.

4. A regulator is provided that steps down the power supply voltage of a DC power supply with the potential of the first terminal as the reference potential to a target voltage and applies the target voltage to the processor. The switching circuit switches the connection switch from off to on in a state where the power supply voltage is equal to or higher than the target voltage. The control device according to any one of claims 1 to 3.

5. The circuit switch has a second control terminal. The circuit switch is on when the voltage of the second control terminal with the potential of the input terminal as the reference potential is equal to or lower than a second predetermined voltage. The switching circuit a circuit resistor connected between the input terminal of the circuit switch and the second control terminal; a second circuit switch connected between the second control terminal of the circuit switch and the second terminal and has The second circuit switch switches from off to on when the voltage of the first terminal with the potential of the second terminal as the reference potential rises to a value equal to or higher than the threshold value. The control device according to any one of claims 1 to 4.

6. A voltage detection circuit is provided that detects the power supply voltage of a DC power supply with the potential of the first terminal as the reference potential. The switching circuit switches the connection switch from off to on when the voltage of the first terminal with the potential of the second terminal as the reference potential rises to a value equal to or higher than the threshold value in a state where the power supply voltage detected by the voltage detection circuit is less than a third predetermined voltage. The control device according to claim 5.

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