Vehicle-mounted current interruption device

Abstract

This technology provides the ability to switch a microcomputer to a power-saving state to reduce power consumption, while simultaneously switching the microcomputer back to an active state if there is a high risk of overcurrent. [Solution] The in-vehicle current cutoff device 20 includes a switch 21 provided between the power supply unit 10 and the load 11, a microcomputer 25 that controls the switch 21, and a startup circuit 26 that performs startup processing to start the microcomputer 25. The microcomputer 25 switches between a startup state and a power-saving state. The microcomputer 25 switches to the startup state when startup processing is performed in the power-saving state. The startup circuit 26 performs startup processing when it determines that the current value supplied from the power supply unit 10 to the load 11 exceeds a first threshold value, while the switch 21 is ON and the microcomputer 25 is in the power-saving state.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an on-vehicle current interrupt device.

BACKGROUND ART

[0002] Patent Document 1 discloses an on-vehicle device. This on-vehicle device includes a microcomputer. The microcomputer performs drive control of an on-vehicle load by performing opening and closing control of an upstream semiconductor switch and a downstream semiconductor switch.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] When it is desired to maintain power supply to the load while putting the microcomputer in a power saving state to reduce the power consumption of the microcomputer, for example, it is conceivable to use a normally-on switch to maintain power supply to the load. However, with this configuration, even if an overcurrent occurs while the microcomputer is in the power saving state, the microcomputer can no longer interrupt the power supply to the load.

[0005] The present disclosure aims to provide a technology capable of switching a microcomputer to an activated state when a situation with a high risk of overcurrent occurs, while switching the microcomputer to a power saving state to reduce power consumption.

MEANS FOR SOLVING THE PROBLEMS

[0006] The on-vehicle current interrupt device of the present disclosure comprises: a switch provided between a power supply unit and a load; a microcomputer that controls the switch; The system includes a startup circuit that performs startup processing for starting the microcomputer, The microcomputer is configured to switch between a startup state and a power-saving state that consumes less power than the startup state, and switches to the startup state when the startup process is performed in the power-saving state. The startup circuit performs the startup process when it determines that the current supplied from the power supply unit to the load exceeds a first threshold value, while the switch is in the ON state and the microcomputer is in the power-saving state. [Effects of the Invention]

[0007] According to the technology disclosed herein, the microcomputer can be switched to a power-saving state to suppress power consumption, and if a situation arises in which there is a high risk of overcurrent, the microcomputer can be switched back to the power-up state. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a diagram showing the configuration of an in-vehicle system including an in-vehicle current interruption device according to the first embodiment. [Figure 2] Figure 2 is a timing chart for when the microcomputer of the first embodiment switches to the startup state and then switches to the off state. [Figure 3] Figure 3 is a timing chart for when the interruption circuit of the first embodiment switches the switch to the off state. [Figure 4] Figure 4 is a diagram showing the configuration of an in-vehicle system including an in-vehicle current interruption device according to the second embodiment. [Figure 5] Figure 5 is a diagram showing the configuration of an in-vehicle system including an in-vehicle current interruption device according to the third embodiment. [Figure 6] Figure 6 is a timing chart for the third embodiment when the microcomputer switches to the startup state and some switches are turned off. [Modes for carrying out the invention]

[0009] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described.

[0010] [1] A switch provided between the power supply unit and the load, A microcomputer that controls the aforementioned switch, The system includes a startup circuit that performs startup processing for starting the microcomputer, The microcomputer is configured to switch between a startup state and a power-saving state that consumes less power than the startup state, and switches to the startup state when the startup process is performed in the power-saving state. The startup circuit performs the startup process when it determines that the current supplied from the power supply unit to the load exceeds a first threshold value, while the switch is in the ON state and the microcomputer is in the power-saving state. Vehicle-mounted current interruption device.

[0011] This configuration allows the microcomputer to enter a power-saving state, thereby reducing its power consumption. Furthermore, when the microcomputer is in a power-saving state, if the current supplied from the power supply to the load exceeds a first threshold, the startup circuit initiates a startup process, switching the microcomputer to the startup state. In other words, with this configuration, even in a power-saving state, the microcomputer switches to the startup state if the current supplied from the power supply to the load exceeds a first threshold. Therefore, while power consumption can be reduced by switching the microcomputer to a power-saving state, the microcomputer can be switched to the startup state if there is a high risk of overcurrent.

[0012] [2] The startup circuit performs the startup process when it determines that the current flowing through the switch exceeds the first threshold value while the switch is in the ON state and the microcomputer is in the power-saving state. The first threshold is less than the smoke generation current value of the electric wire constituting the conductive path provided with the switch The on-vehicle current interrupting device according to [1].

[0013] According to this configuration, the microcomputer can be easily switched to the activated state before the electric wire constituting the conductive path provided with the switch emits smoke.

[0014] [3] The activation circuit performs the activation process when determining that the current value flowing through the switch exceeds the first threshold in a state where the switch is in an on-state and the microcomputer is in the power saving state, The first threshold is equal to or greater than the current value that can be supplied to the load The on-vehicle current interrupting device according to [1] or [2].

[0015] According to this configuration, it is easy to avoid the microcomputer being switched to the activated state in a state where current is normally supplied to the load.

[0016] [4] The activation circuit performs the activation process when determining that the current value flowing through the switch exceeds the first threshold in a state where the switch is in an on-state and the microcomputer is in the power saving state, The microcomputer switches the switch to an off-state when determining that the current value flowing through the switch in the activated state exceeds a second threshold, The second threshold is larger than the first threshold The on-vehicle current interrupting device according to any one of [1] to [3].

[0017] According to this configuration, the microcomputer can be easily switched to the activated state before the current value flowing through the switch exceeds the second threshold which is the interruption condition by the microcomputer.

[0018] [5] When the microcomputer determines that the current value flowing through the switch in the startup state has exceeded the second threshold for a predetermined period of time, it switches the switch to the off state. Furthermore, the system includes a cutoff circuit that switches the switch to the off state when it is determined that the current flowing through the switch exceeds a third threshold. The third threshold is greater than the second threshold. The vehicle-mounted current interruption device described in [4].

[0019] With this configuration, if the current flowing through the switch exceeds a second threshold for a predetermined period of time, the microcomputer can switch the switch to the off state. Furthermore, even if the condition of exceeding the second threshold does not persist for a predetermined period of time, if the current flowing through the switch exceeds a third threshold, the cutoff circuit can switch the switch to the off state.

[0020] [6] The startup circuit performs the startup process when it determines that the current flowing through the switch exceeds the first threshold value while the switch is in the ON state and the microcomputer is in the power-saving state. Furthermore, the system includes a cutoff circuit that switches the switch to the off state when it is determined that the current flowing through the switch exceeds a third threshold. The third threshold is greater than the first threshold. An on-board current interruption device as described in any of [1] to [3].

[0021] With this configuration, when the microcomputer is in a power-saving state, if the current flowing through the switch increases sharply and exceeds the first threshold to reach the third threshold, the cutoff circuit can switch the switch to the off state.

[0022] [7] Multiple loads are provided, The power paths connecting the power supply unit to each of the loads include a common path connected to the power supply unit and branch paths that branch off from the common path and connect to each of the loads. The aforementioned switches are provided in each of the aforementioned branch paths. The startup circuit performs the startup process when it determines that the current flowing through any of the switches exceeds the first threshold value. An on-board current interruption device as described in any of [1] to [6].

[0023] In this configuration, in a setup with multiple loads, the microcomputer can be switched to the powered-on state when the current flowing through any of the switches exceeds a first threshold.

[0024] [8] Multiple loads are provided, The power paths connecting the power supply unit to each of the loads include a common path connected to the power supply unit and branch paths that branch off from the common path and connect to each of the loads. The aforementioned switches are provided in each of the aforementioned branch paths. The startup circuit performs the startup process when it determines that the current flowing through the common path exceeds the first threshold value, while each of the switches is in the ON state and the microcomputer is in the power-saving state. The vehicle-mounted current interruption device described in [1].

[0025] With this configuration, in a configuration with multiple loads, the microcomputer can be switched to an activated state when the current value flowing through the common path exceeds a first threshold.

[0026] [9] The first threshold is less than the sum of the smoke current values ​​of each wire constituting each branch path. The vehicle-mounted current interruption device described in [8].

[0027] This configuration makes it easier to switch the microcomputer to the powered-on state before the wires constituting each branch path start to emit smoke.

[0028]

[10] The first threshold is equal to or greater than the sum of the current values ​​that can be supplied to each of the loads. The vehicle-mounted current interruption device described in [8] or [9].

[0029] This configuration makes it easier to avoid the microcomputer switching to the startup state while current is being supplied normally to each load.

[0030]

[11] A current detection unit is provided for detecting the current value supplied from the power supply unit to the load, The startup circuit determines, based on the signal output from the current detection unit, whether the current value supplied from the power supply unit to the load exceeds the first threshold value. The switch and the current detection unit are configured as an integrated current detector (IPD). An on-board current interruption device as described in any of [1] to

[10] .

[0031] With this configuration, the startup circuit can determine whether the current supplied from the power supply unit to the load exceeds a first threshold value based on a signal output from a current sensing unit integrated with the switch.

[0032] [Details of the embodiments of this disclosure] 1. First Embodiment Figure 1 shows an in-vehicle system 1 including an in-vehicle current interruption device 20 according to a first embodiment. The in-vehicle system 1 is a system mounted on a vehicle. The in-vehicle system 1 comprises a power supply unit 10, a load 11, and a power line 12. The power line 12 is provided between the power supply unit 10 and the load 11 and supplies power from the power supply unit 10 to the load 11. At least a portion of the power line 12 is made up of electric wires.

[0033] The in-vehicle current interruption device 20 comprises a switch 21, a current detection unit 22, a drive signal output unit 23, a changeover switch 24, a microcomputer 25 (hereinafter also referred to as microcontroller 25), a start circuit 26, an interruption circuit 27, and an AND circuit 28.

[0034] Switch 21 is provided in the power line 12. Switch 21 is provided between the power supply unit 10 and the load 11 and switches between an ON state that allows current to flow from the power supply unit 10 to the load 11 through itself and an OFF state that prevents current from flowing from the power supply unit 10 to the load 11 through itself. In this embodiment, switch 21 is a normally-off type switch. In this embodiment, switch 21 is a semiconductor switching element, specifically an N-channel MOSFET.

[0035] The current detection unit 22 detects the current value flowing from the power supply unit 10 to the load 11. The current detection unit 22 also detects the current value flowing through the switch 21. The current value flowing through the switch 21 is the current value flowing through the switch 21 when the switch 21 is in the ON state. The current detection unit 22 is configured, for example, by a known current sensor. The current detection unit 22 outputs a signal indicating the detection result. The switch 21 and the current detection unit 22 are configured as an integrated IPD 30. The IPD 30 is an Intelligent Power Device.

[0036] The drive signal output unit 23 generates a drive signal to drive the switch 21 and outputs it toward the input unit 21A (gate in this embodiment) of the switch 21. The drive signal output unit 23 always outputs a high-level signal as the drive signal. The drive signal output unit 23 is configured to include, for example, an LDO (Low Drop Out).

[0037] The changeover switch 24 is provided between the input section 21A and the drive signal output section 23 of the switch 21. The changeover switch 24 switches between an ON state, which allows the drive signal output from the drive signal output section 23 to be input to the input section 21A of the switch 21, and an OFF state, which blocks the drive signal output from the drive signal output section 23. In this embodiment, the changeover switch 24 is a normally-on type switch. In this embodiment, the changeover switch 24 is a semiconductor switching element, specifically a P-channel type MOSFET.

[0038] The drive signal output unit 23 described above always outputs a drive signal. Therefore, when the changeover switch 24 is in the ON state, an ON signal is output to the switch 21, and when the changeover switch 24 is in the OFF state, an OFF signal is output to the switch 21.

[0039] The microcontroller 25 controls switch 21. The microcontroller 25 controls switch 21 by controlling changeover switch 24. The microcontroller 25 controls changeover switch 24 to the OFF state and switches 21 to the OFF state by applying a high-level signal to the input 24A (gate in this embodiment) of changeover switch 24 of changeover switch 24. The microcontroller 25 controls changeover switch 24 to the ON state and switches 21 to the ON state by applying a low-level signal to the input 24A (gate in this embodiment) of changeover switch 24

[0040] The microcontroller 25 switches between a startup state and a power-saving state, which consumes less power than the startup state. The microcontroller 25 may enter the startup state when, for example, the vehicle's start switch is turned ON, and enter the power-saving state when the start switch is turned OFF. The start switch may be, for example, an ignition switch or a power switch. In the startup state, the microcontroller 25 controls switch 21. In the power-saving state, the microcontroller 25 does not control switch 21. When the microcontroller 25 is in the power-saving state, the changeover switch 24 is not controlled, so the changeover switch 24 is turned ON, and an ON signal is output to switch 21.

[0041] The startup circuit 26 is a circuit that performs startup processing to start the microcontroller 25. The startup circuit 26 performs startup processing when it determines that the current supplied from the power supply unit 10 to the load 11 exceeds a first threshold value, while the switch 21 is ON and the microcontroller 25 is in a power-saving state. In other words, the startup circuit 26 performs startup processing when it determines that the current flowing through the switch 21 exceeds a first threshold value.

[0042] With this configuration, the power consumption of the microcontroller 25 can be suppressed by putting it into a power-saving state. Furthermore, when the microcontroller 25 is in a power-saving state, if the current supplied from the power supply unit 10 to the load 11 exceeds a first threshold, the startup circuit 26 performs a startup process, and the microcontroller 25 switches to the startup state. In other words, with the in-vehicle current cutoff device 20, even when the microcontroller 25 is in a power-saving state, if the current supplied from the power supply unit 10 to the load 11 exceeds a first threshold, it switches to the startup state. Therefore, while suppressing power consumption by switching the microcontroller 25 to a power-saving state, the microcontroller 25 can be switched to the startup state if there is a high risk of overcurrent occurring.

[0043] The first threshold is less than the smoke current value of the wires constituting the power line 12. The smoke current value is the current value at which smoke is produced when current flows through the wire for a certain period of time. The shorter the period, the higher the value, and the longer the period, the lower the value. However, there is a current value at which smoke is not produced even if the current flows indefinitely, and being below the upper limit of this current value corresponds to being less than the smoke current value. With this configuration, it is easy to switch the microcontroller 25 to the powered state before the wires constituting the power line 12 start smoking.

[0044] Furthermore, the first threshold is greater than or equal to the current value that can be supplied to the load 11. The current value that can be supplied to the load 11 is the maximum current value that can be supplied to the load 11, for example, the rated current of the load 11. With this configuration, it is easier to avoid the microcontroller 25 switching to the startup state while current is being supplied to the load 11 normally.

[0045] The startup circuit 26 identifies the current value supplied from the power supply unit 10 to the load 11 based on the signal output from the current detection unit 22. The startup circuit 26 then determines whether the identified current value exceeds a first threshold. The startup circuit 26 does not need to determine whether the switch 21 is ON and the microcontroller 25 is in a power-saving state; it only needs to perform the startup process if it determines that the current value supplied from the power supply unit 10 to the load 11 exceeds the first threshold, at least when the switch 21 is ON and the microcontroller 25 is in a power-saving state.

[0046] In this embodiment, the startup process is the process of sending a startup signal to the microcontroller 25. The microcontroller 25 switches to the startup state when the startup process is performed in a power-saving state. In other words, when the microcontroller 25 receives a startup signal in a power-saving state, it switches to the startup state. The startup circuit 26 is composed of, for example, a comparator or a logic IC.

[0047] The microcontroller 25 switches the switch 21 to the off state if it determines that the current flowing through the switch 21 has become an overcurrent during startup. Based on the signal output from the current detection unit 22, the microcontroller 25 identifies the current value supplied from the power supply unit 10 to the load 11. The microcontroller 25 then determines whether the identified current value exceeds a second threshold, and if it determines that it has exceeded the second threshold, it switches the switch 21 to the off state. The second threshold is greater than the first threshold.

[0048] With this configuration, it is easier to switch the microcontroller 25 to the powered-on state before the current flowing through switch 21 exceeds the second threshold, which is the tripping condition set by the microcontroller 25.

[0049] The interruption circuit 27 switches the switch 21 to the off state when it determines that the current flowing through the switch 21 exceeds the third threshold. The interruption circuit 27 identifies the current flowing through the switch 21 based on the signal output from the current detection unit 22. The interruption circuit 27 then determines whether the identified current value exceeds the third threshold. If the identified current value does not exceed the third threshold, the interruption circuit 27 outputs a high-level signal. If the interruption circuit 27 determines that the current value has exceeded the third threshold, it outputs a low-level signal to switch the switch 21 to the off state. The interruption circuit 27 is composed of, for example, a comparator or a logic IC. The interruption circuit 27 immediately switches the switch 21 to the off state when it determines that the current flowing through the switch 21 exceeds the third threshold.

[0050] The AND circuit 28 has a first input section 28A, a second input section 28B, and an output section 28C. The signal output from the drive signal output section 23 is input to the first input section 28A via the changeover switch 24. The signal output from the cutoff circuit 27 is input to the second input section 28B. When high-level signals are input to both the first input section 28A and the second input section 28B, the AND circuit 28 outputs a high-level signal from the output section 28C. When a low-level signal is input to at least one of the first input section 28A and the second input section 28B, the AND circuit 28 outputs a low-level signal from the output section 28C. The signal output from the output section 28C is input to the input section 21A of the switch 21.

[0051] The microcontroller 25 described above does not immediately switch the switch 21 to the off state when the current flowing through the switch 21 exceeds the second threshold during startup. The microcontroller 25 switches the switch 21 to the off state when it determines that the current flowing through the switch 21 has exceeded the second threshold for a predetermined period of time during startup. The third threshold described above is greater than the second threshold.

[0052] With this configuration, if it is determined that the current flowing through switch 21 exceeds the second threshold for a predetermined period of time, the microcontroller 25 can switch switch 21 to the off state. Furthermore, even if the condition exceeding the second threshold does not continue for a predetermined period of time, if the current flowing through switch 21 exceeds the third threshold, the cutoff circuit 27 can switch switch 21 to the off state.

[0053] Furthermore, the third threshold is greater than the first threshold. With this configuration, when the microcontroller 25 is in a power-saving state, if the current flowing through the switch 21 increases sharply and exceeds the first threshold to reach the third threshold, the cutoff circuit 27 can switch the switch to the off state.

[0054] Figure 2 shows a timing chart for when the microcontroller 25 switches to the power-up state and the switch 21 is switched to the off state. In the example shown in Figure 2, at timing t0, the microcontroller 25 is in a power-saving state, and the cutoff circuit 27 controls the switch 21 to the ON state. As a result, the AND circuit 28 outputs a high-level signal, and the switch 21 is in the ON state. At this point, the current flowing through the switch 21 is greater than 0A and less than the first threshold.

[0055] Subsequently, at timing t1, the current value begins to rise. At timing t2, when the current value exceeds the first threshold, the startup circuit 26 performs the startup process, and the microcontroller 25 switches to the startup state. At this time, since the current value has not exceeded the second threshold, the microcontroller 25 controls the switch 21 to the ON state.

[0056] Subsequently, at timing t3, the current value exceeds the second threshold, and at timing t4, if the current value remains above the second threshold for a predetermined period of time, the microcontroller 25 controls the switch 21 to the off state. As a result, the AND circuit 28 outputs a low-level signal, and the switch 21 switches to the off state.

[0057] Figure 3 shows a timing chart for when the interruption circuit 27 switches switch 21 to the off state. In the example shown in Figure 3, at timing t10, the microcontroller 25 is in a power-saving state, and the interruption circuit 27 controls switch 21 to the on state. As a result, the AND circuit 28 controls switch 21 to the on state. At this point, the current flowing through switch 21 is greater than 0A and less than the first threshold.

[0058] Subsequently, at timing t11, the current value begins to rise sharply. At timing t12, when the current value exceeds the first threshold, the startup circuit 26 performs the startup process, and the microcontroller 25 switches to the startup state. At this time, since the current value has not exceeded the second threshold, the microcontroller 25 controls the switch 21 to the ON state. Subsequently, at timing t13, when the current value exceeds the third threshold, the cutoff circuit 27 controls the switch 21 to the OFF state. The AND circuit 28 outputs a low-level signal, and the switch 21 switches to the OFF state.

[0059] 2. Second Embodiment In the second embodiment, a configuration in which multiple loads are provided will be described. In the second embodiment, the same reference numerals are used for components that are the same as in the first embodiment, and detailed explanations are omitted.

[0060] Figure 4 shows an in-vehicle system 201 including an in-vehicle current interruption device 220 according to a second embodiment. The in-vehicle system 201 is a system mounted on a vehicle. The in-vehicle system 201 comprises a power supply unit 10, a plurality of loads 211A, 211B, 211C, and a power line 212.

[0061] The power line 212 is connected from the power supply unit 10 to each load 211A, 211B, and 211C, and supplies power from the power supply unit 10 to each load 211A, 211B, and 211C. The power line 212 includes a common path 212Z connected to the power supply unit 10, and branch paths 212A, 212B, and 212C that branch off from the common path 212Z and connect to each load 211A, 211B, and 211C. At least a portion of each branch path 212A, 212B, and 212C is made up of electric wires.

[0062] The in-vehicle current interruption device 220 comprises a plurality of switches 221A, 221B, 221C, a plurality of current detection units 222A, 222B, 222C, a drive signal output unit 223, a plurality of changeover switches 224A, 224B, 224C, a microcomputer 225 (hereinafter also referred to as microcontroller 225), a start circuit 226, a plurality of interruption circuits 227A, 227B, 227C, and a plurality of AND circuits 228A, 228B, 228C.

[0063] In this embodiment, switches 221A, 221B, and 221C are normally-off switches and N-channel MOSFETs. Switch 221A is provided in branch path 212A, switch 221B is provided in branch path 212B, and switch 221C is provided in branch path 212C.

[0064] Each current detection unit 222A, 222B, and 222C is provided in correspondence with each switch 221A, 221B, and 221C, and detects the current value flowing through the switch 221A, 221B, and 221C corresponding to itself. Switch 221A and current detection unit 222A are integrated as IPD230A, switch 221B and current detection unit 222B are integrated as IPD230B, and switch 221C and current detection unit 222C are integrated as IPD230C.

[0065] Each of the selector switches 224A, 224B, and 224C in this embodiment is a normally-on type switch and a P-channel type MOSFET. Each of the selector switches 224A, 224B, and 224C is provided corresponding to each of the switches 221A, 221B, and 221C, and can block the drive signals output from the drive signal output unit 223 to the corresponding switches 221A, 221B, and 221C.

[0066] The microcontroller 225 controls the on / off state of each switch 221A, 221B, and 221C by controlling the on / off state of each changeover switch 224A, 224B, and 224C, similar to the configuration of the first embodiment.

[0067] The microcontroller 225 identifies the current value flowing through each switch 221A, 221B, and 221C based on the signals output from the current sensing units 222A, 222B, and 222C. The microcontroller 225 determines whether the current value flowing through any of the switches 221A, 221B, and 221C exceeds the second threshold. If the microcontroller 225 determines that the current value flowing through any of the switches 221A, 221B, and 221C exceeds the second threshold, it controls the switch whose current value exceeds the second threshold to the OFF state. The second threshold may be set commonly for all switches 221A, 221B, and 221C, or it may be set differently for each switch 221A, 221B, and 221C.

[0068] The microcontroller 225 switches between a startup state and a power-saving state, which consumes less power than the startup state. The startup circuit 226 performs a startup process when it determines that the current supplied from the power supply unit 10 to the load via the ON switches exceeds a first threshold, while some or all of the switches 221A, 221B, and 221C are ON and the microcontroller 225 is in a power-saving state. The microcontroller 225 switches to the startup state when the startup process is performed in the power-saving state. The first threshold may be set commonly for all switches 221A, 221B, and 221C, or it may be set differently for each switch 221A, 221B, and 221C. The first threshold is less than the smoke current value of the wires constituting the branch path where the switch corresponding to it is provided. The first threshold is greater than or equal to the current value that can be supplied to the load corresponding to it. The second threshold described above is greater than the first threshold corresponding to the same switch. For example, the second threshold corresponding to switch 221A is greater than the first threshold corresponding to switch 221A.

[0069] The microcontroller 225, in the startup state, switches any of switches 221A, 221B, or 221C to the OFF state if it determines that the current flowing through that switch has exceeded the second threshold for a predetermined period of time.

[0070] Each of the interruption circuits 227A, 227B, and 227C is provided in correspondence with each of the switches 221A, 221B, and 221C. Each of the interruption circuits 227A, 227B, and 227C switches its corresponding switch 221A, 221B, and 221C to the OFF state when it determines that the current flowing through the switch 221A, 221B, and 221C has exceeded the third threshold. Each of the interruption circuits 227A, 227B, and 227C identifies the current flowing through the switch 221A, 221B, and 221C corresponding to it based on the signal output from 222A, 222B, and 222C. Then, each of the interruption circuits 227A, 227B, and 227C determines whether the identified current value has exceeded the third threshold. The third threshold may be set commonly for all switches 221A, 221B, and 221C, or it may be set differently for each switch 221A, 221B, and 221C. The third threshold is greater than the second threshold for the same switch and greater than the first threshold for the same switch.

[0071] Each AND circuit 228A, 228B, and 228C is provided in correspondence with each switch 221A, 221B, and 221C. Each AND circuit 228A, 228B, and 228C outputs a high-level signal to the corresponding 221A, 221B, and 221C when a high-level signal is output to the corresponding 221A, 221B, and 221C via the changeover switch 224A, 224B, and 224C, and when a high-level signal is output from the cutoff circuit 227A, 227B, and 227C, thereby controlling the corresponding 221A, 221B, and 221C to the ON state. Each AND gate 228A, 228B, and 228C outputs a low-level signal to its corresponding gates 221A, 221B, and 221C when a low-level signal is output to them via the changeover switches 224A, 224B, and 224C, or when a low-level signal is output to the cutoff gates 227A, 227B, and 227C, thereby controlling the corresponding gates 221A, 221B, and 221C to the OFF state.

[0072] 3. Third Embodiment In the third embodiment, we will describe an example in which a startup process is performed when the current value flowing through the common path exceeds a first threshold in a configuration where multiple loads are provided. In the third embodiment, the same reference numerals are used for components that are the same as in the second embodiment, and detailed explanations are omitted.

[0073] Figure 5 shows the in-vehicle system 301 of the third embodiment. The in-vehicle system 301 includes an in-vehicle current interruption device 320 instead of the in-vehicle current interruption device 220 described in the second embodiment. The in-vehicle current interruption device 320 includes a start circuit 326 instead of the start circuit 226 described in the second embodiment. Furthermore, the in-vehicle current interruption device 320 includes a current detection unit 322 that detects the current value flowing through the common path 212Z.

[0074] The startup circuit 326 performs startup processing when it determines that the current flowing through the common path 212Z exceeds a first threshold, while all switches 221A, 221B, and 221C are ON and the microcontroller 225 is in a power-saving state. The startup circuit 326 identifies the current flowing through the common path 212Z based on the signal output from the current detection unit 322. The startup circuit 326 determines whether the identified current value exceeds the first threshold, and performs startup processing if it determines that it has exceeded the first threshold.

[0075] The first threshold is less than the sum of the smoke current values ​​of each wire constituting each branch path 212A, 212B, 212C. The first threshold is greater than or equal to the sum of the current values ​​that can be supplied to each load 211A, 211B, 211C. The first threshold is less than the sum of the second thresholds corresponding to each switch 221A, 221B, 221C. The first threshold may be less than any of the second thresholds corresponding to any of the switches 221A, 221B, 221C. The first threshold is less than the sum of the third thresholds corresponding to each switch 221A, 221B, 221C. The first threshold may be less than any of the third thresholds corresponding to any of the switches 221A, 221B, 221C. The sum of the second thresholds corresponding to each switch 221A, 221B, 221C is less than the sum of the third thresholds corresponding to each switch 221A, 221B, 221C.

[0076] Figure 6 shows a timing chart for when the microcontroller 225 switches to the power-up state and switches switch 221A to the off state. In the example shown in Figure 6, at timing t20, the microcontroller 225 is in a power-saving state, and each cutoff circuit 227A, 227B, and 227C controls its corresponding 221A, 221B, and 221C to be ON. As a result, each AND circuit 228A, 228B, and 228C outputs a high-level signal, and each switch 221A, 221B, and 221C is ON. At this point, the current flowing through each switch 221A, 221B, and 221C is greater than 0A and less than the first threshold.

[0077] Subsequently, at timing t21, the current value begins to rise. At timing t22, when the current value flowing through the common path 212Z exceeds the first threshold, the startup circuit 326 performs the startup process, and the microcontroller 225 switches to the startup state. At this time, since the current value has not exceeded the second threshold, the microcontroller 225 controls switches 221A, 221B, and 221C to the ON state.

[0078] Subsequently, at timing t23, the current flowing through switch 221A exceeds the second threshold corresponding to switch 221A, and at timing t24, if the current flowing through switch 221A remains above the second threshold corresponding to switch 221A for a predetermined period of time, the microcontroller 225 controls switch 221A to the off state. As a result, the AND circuit 228A outputs a low-level signal, and switch 221A switches to the off state.

[0079] <Other Embodiments> This disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of the features of the embodiments described above or below is possible as long as it does not contradict each other. Furthermore, any feature of the embodiments described above or below may be omitted unless explicitly stated as essential. In addition, the embodiments described above may be modified as follows.

[0080] In the embodiments described above, the switch provided between the power supply and the load was a normally-off switch, but a normally-on switch may also be used. In this case, there is no need to provide a changeover switch and a drive signal output unit, and the microcomputer can directly control the switch.

[0081] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0082] 1…In-vehicle systems 10...Power supply section 11…Load 12…Power line 20... Vehicle-mounted current interruption device 21…Switch 21A...Input section 22...Current detection unit 23...Drive signal output section 24... Changeover switch 24A...Input section 25… Microcomputer 26...Startup circuit 27...Blocking circuit 28... AND gate 28A...First input section 28B...Second input section 28C…Output section 30…IPD 201... In-vehicle systems 211A...Load 211B...Load 211C...Load 212…Power line 212A... Branch route 212B... Branch route 212C... Branch route 212Z... Common route 220... Vehicle-mounted current interruption device 221A…Switch 221B... Switch 221C... Switch 222A...Current detection unit 222B...Current detection unit 222C...Current detection unit 223...Drive signal output section 224A... Changeover switch 224B... Changeover switch 224C... Changeover switch 225... Microcomputer 226...Startup circuit 227A...Breakdown circuit 227B...Blocking circuit 227C...Block circuit 228A…AND circuit 228B…AND circuit 228C…AND circuit 230A…IPD 230B…IPD 230°C…IPD 301... In-vehicle systems 320... Vehicle-mounted current interruption device 322...Current detection unit 326...Startup circuit

Claims

1. A switch is provided between the power supply unit and the load, A microcomputer that controls the aforementioned switch, The system includes a startup circuit that performs startup processing for starting the microcomputer, The microcomputer is configured to switch between a startup state and a power-saving state that consumes less power than the startup state, and switches to the startup state when the startup process is performed in the power-saving state. The startup circuit performs the startup process when it determines that the current supplied from the power supply unit to the load exceeds a first threshold value, while the switch is ON and the microcomputer is in the power-saving state. Vehicle-mounted current interruption device.

2. The startup circuit performs the startup process when it determines that the current flowing through the switch exceeds the first threshold value while the switch is in the ON state and the microcomputer is in the power-saving state. The first threshold value is less than the smoke current value of the wires constituting the conductive path in which the switch is provided. The vehicle-mounted current interruption device according to claim 1.

3. The startup circuit performs the startup process when it determines that the current flowing through the switch exceeds the first threshold value while the switch is in the ON state and the microcomputer is in the power-saving state. The first threshold value is greater than or equal to the current value that can be supplied to the load. The vehicle-mounted current interruption device according to claim 1 or claim 2.

4. The startup circuit performs the startup process when it determines that the current flowing through the switch exceeds the first threshold value while the switch is in the ON state and the microcomputer is in the power-saving state. The microcomputer, when it determines that the current flowing through the switch in the startup state exceeds a second threshold, switches the switch to the off state. The second threshold is greater than the first threshold. The vehicle-mounted current interruption device according to claim 1 or claim 2.

5. The microcomputer, when it determines that the current flowing through the switch has exceeded the second threshold for a predetermined period of time in the startup state, switches the switch to the off state. Furthermore, the system includes a cutoff circuit that switches the switch to the off state when it is determined that the current flowing through the switch exceeds a third threshold. The third threshold is greater than the second threshold. The vehicle-mounted current interruption device according to claim 4.

6. The startup circuit performs the startup process when it determines that the current flowing through the switch exceeds the first threshold value while the switch is in the ON state and the microcomputer is in the power-saving state. Furthermore, the system includes a cutoff circuit that switches the switch to the off state when it is determined that the current flowing through the switch exceeds a third threshold. The third threshold is greater than the first threshold. The vehicle-mounted current interruption device according to claim 1.

7. Multiple loads are provided, The power paths connecting the power supply unit to each of the loads include a common path connected to the power supply unit and branch paths that branch off from the common path and connect to each of the loads. The aforementioned switches are provided in each of the aforementioned branch paths. The startup circuit performs the startup process when it determines that the current flowing through any of the switches exceeds the first threshold value. The vehicle-mounted current interruption device according to claim 1 or claim 2.

8. Multiple loads are provided, The power paths connecting the power supply unit to each of the loads include a common path connected to the power supply unit and branch paths that branch off from the common path and connect to each of the loads. The aforementioned switches are provided in each of the aforementioned branch paths. The startup circuit performs the startup process when it determines that the current flowing through the common path exceeds the first threshold value, while each of the switches is in the ON state and the microcomputer is in the power-saving state. The vehicle-mounted current interruption device according to claim 1.

9. The first threshold is less than the sum of the smoke current values ​​of each wire constituting each branch path. The vehicle-mounted current interruption device according to claim 8.

10. The first threshold value is equal to or greater than the sum of the current values ​​that can be supplied to each of the loads. The vehicle-mounted current interruption device according to claim 8 or claim 9.

11. The power supply unit is equipped with a current detection unit that detects the current value supplied to the load, The startup circuit determines, based on the signal output from the current detection unit, whether the current value supplied from the power supply unit to the load exceeds the first threshold value. The switch and the current detection unit are configured as an integrated device (IPD). The vehicle-mounted current interruption device according to claim 1 or claim 2.

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