JP2019177722A - On-vehicle power supply control device - Google Patents

Abstract

To provide (an on-vehicle power supply control device) for restraining unnecessarily delaying stating of a load when an accessory power source is turned on.SOLUTION: A control unit 15 of an on-vehicle power supply control device 1 controls a power supply circuit 14 so as to stop supply of electric power to an integrated circuit 3 when an accessory power source 4 is turned off, and when a first time passes without turning on the accessory power source 4 from the timing for stopping the electric power supply, while setting a value of a flag stored in a RAM 17 to a specific value, when the accessory power source 4 is turned on, when the value of the flag is the specific value, the power supply circuit 14 is controlled so as to start the supply of the electric power to a load in response to ON of the accessory power source 4, and the flag is set as a value different from the specific value, and thus, when the accessory power source 4 is turned on, when the first time passes after stopping the supply of the electric power, the supply of the electric power to the integrated circuit 3 is immediately started.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle-mounted power supply control device, and is particularly suitable for use in a vehicle-mounted power supply control device having a power supply circuit that supplies power to a load provided in a vehicle.

  Conventionally, for an in-vehicle power supply control device provided in a vehicle, a control unit supplies power to various loads (such as a control circuit that controls a device provided in the vehicle) when an accessory power supply is turned on. In some cases, the start of power supply to the load is instructed so that power is supplied from the power supply circuit to the load. In a conventional in-vehicle power supply control device, when the accessory power supply is turned on, the control unit does not cause the power supply circuit to supply power to the load immediately, but the power to the load after a certain period of time has passed. To supply. This is so that the charge accumulated in the capacitor of the load before the load is restarted is sufficiently discharged, and when the load is restarted, the load starts up from the power supply voltage of zero potential. That is, even if the accessory power supply is turned off and on in a very short time because the power is supplied to the load after a certain period of time has elapsed after the accessory power supply is turned on. A certain period is reliably ensured as a period in which power is not supplied to the load, and the charge accumulated in the capacitor of the load is sufficiently discharged during that period.

  In Patent Document 1, a main switch that enables power supply from the battery to the motor is provided, and when an abnormality (overcurrent, etc.) occurs, the power supply to the motor is automatically stopped. Thus, in addition to the main switch, there is described an electric device provided with an initialization switch that can release the stop of power supply to the motor due to the occurrence of an abnormality. According to the electric device described in Patent Document 1, the user can cancel the power supply stop by using an initialization switch provided separately from the main switch. It is possible to suppress the risk that it cannot be released (the power circuit cannot be restarted).

JP 2017-158401 A

  As described above, in the conventional in-vehicle power supply control device, when the accessory power supply is turned on, the control unit causes the power supply circuit to start supplying power after a certain period of time has elapsed. Due to such a configuration, even when the charge of the capacitor of the load is already sufficiently discharged, it is always between the timing when the accessory power supply is turned on and the time when the supply of power to the load is started. There is a case where a standby time occurs, and load activation (start of supply of power to the load) is unnecessarily delayed.

  The present invention has been made to solve such a problem, and an object of the present invention is to suppress unnecessarily delayed start of a load when an accessory power source is turned on.

  In order to solve the above-described problems, an in-vehicle power supply control device according to the present invention is based on a control unit that controls a power supply circuit based on an accessory power supply, and electric power supplied from an in-vehicle battery based on control from the control unit. And a power supply circuit for controlling start and stop of supply of power to the load. The control unit controls the power supply circuit to stop the supply of power to the load when the accessory power supply is turned off, and the first time without turning on the accessory power supply from the timing of the power supply stop. Is passed, the flag value stored in the memory is set as a specific value indicating that the first time has passed without the accessory power being turned on, while the flag value is stored when the accessory power is turned on. When is a specific value, the power supply circuit is controlled to start supplying power to the load when the accessory power supply is turned on, the flag is set to a value different from the specific value, and the flag value is not the specific value Sets the power supply circuit to start supplying power to the load at the timing when the second time elapses from when the accessory power supply is turned on. To your.

  According to the present invention configured as described above, it is managed whether or not the first time necessary for the charge of the capacitor of the load to be sufficiently discharged after the accessory power source is turned off has elapsed. Then, when the accessory power is turned on and the first time has elapsed after the accessory power is turned off, the power supply circuit immediately supplies power to the addition without waiting for the second time. Is started. For this reason, it can suppress that starting of load unnecessarily delays.

It is a block diagram which shows the hardware structural example of the vehicle-mounted power supply control apparatus which concerns on one Embodiment of this invention. It is a timing chart used for description of operation | movement of the control unit in a 1st case. It is a timing chart used for description of operation | movement of the control unit in a 2nd case. It is a timing chart used for explanation of operation of a control unit in the 3rd case.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a hardware configuration example of the in-vehicle power supply control device 1 according to the present embodiment. The on-vehicle power supply control device 1 is a device mounted on a vehicle, and when the accessory power supply 4 of the vehicle is turned on by a user, the power (power supply voltage) supplied from the on-vehicle battery 2 is converted into a predetermined voltage and integrated. When the power is supplied to the circuit 3 (corresponding to the “load” in the claims) and the accessory power supply 4 is turned off, the power supply to the integrated circuit 3 is stopped.

  The integrated circuit 3 is a control circuit that controls various devices (for example, an audio device, a broadcast receiving device, and an air conditioner) provided in the vehicle, for example. A capacitor is mounted on the integrated circuit 3 for the purpose of voltage stabilization in the circuit and other purposes, so that the discharge of the charge accumulated in the capacitor is completed after the integrated circuit 3 is once shut down and restarted. Therefore, when the load is restarted, it is necessary that the load rises from the zero-potential power supply voltage. In the present embodiment, the shutdown of the integrated circuit 3 means the stop of power supply to the integrated circuit 3, and the activation of the integrated circuit 3 means the start of power supply to the integrated circuit 3. .

  As shown in FIG. 1, the in-vehicle power supply control device 1 includes a battery detection circuit 10, a constant power supply circuit 11, a reset signal generation circuit 12, an accessory power supply detection circuit 13, a power supply circuit 14, a control unit 15, and a nonvolatile memory 16. .

  The battery detection circuit 10 is connected to a first power supply line 20 connected to the in-vehicle battery 2, detects whether or not the power supply voltage of the in-vehicle battery 2 is equal to or higher than a predetermined voltage, and a battery detection signal corresponding to the detection result. TX1 is output to the control unit 15. More specifically, the battery detection circuit 10 continues to output the high-level battery detection signal TX1 to the control unit 15 while the power supply voltage of the in-vehicle battery 2 is equal to or higher than the predetermined voltage, and continues while it is lower than the predetermined voltage. The low level battery detection signal TX1 is output to the control unit 15.

  The constant power supply circuit 11 is connected to the first power supply line 20, converts the power supplied from the in-vehicle battery 2 into a predetermined voltage, and passes through the second power supply line 21 to the reset signal generation circuit 12 and the control unit 15. Supply.

  The reset signal generation circuit 12 is connected to the second power supply line 21 and detects whether or not the power supply voltage of the power supply circuit 11 is always equal to or higher than a predetermined voltage, and outputs a reset control signal TX2 corresponding to the detection result to the control unit 15. Output to. More specifically, the reset signal generation circuit 12 continuously outputs the high level reset control signal TX2 to the control unit 15 while the power supply voltage of the power supply circuit 11 is equal to or higher than the predetermined voltage, and while the power supply voltage is below the predetermined voltage. The low level reset control signal TX2 is continuously output to the control unit 15. When the low level reset control signal TX2 is input to the control unit 15, the control unit 15 is reset. Thereafter, when the level of the reset control signal TX2 is switched from the low level to the high level, the reset of the control unit 15 is released and the control unit 15 is activated.

  The accessory power supply detection circuit 13 is connected to the third power supply line 22 connected to the accessory power supply 4, detects whether or not the power supply voltage of the accessory power supply 4 is equal to or higher than a predetermined voltage, and the accessory power supply according to the detection result. The detection signal TX3 is output to the control unit 15. When the accessory power supply 4 is turned on by the user, the power supply voltage of the accessory power supply 4 becomes a predetermined voltage or higher, and when the accessory power supply 4 is turned off, the power supply voltage of the accessory power supply 4 falls below the predetermined voltage. The accessory power supply detection circuit 13 continuously outputs a high-level accessory power supply detection signal TX3 to the control unit 15 while the power supply voltage of the accessory power supply 4 is equal to or higher than a predetermined voltage, and continues to be low level when the power supply voltage is lower than the predetermined voltage. The accessory power supply detection signal TX3 is output to the control unit 15.

  The power supply circuit 14 is connected to the first power supply line 20 and the fourth power supply line 23, converts the power supplied from the in-vehicle battery 2 through the first power supply line 20 to a predetermined voltage, and supplies the fourth power. This is supplied to the integrated circuit 3 via the line 23. More specifically, when the power supply circuit 14 receives a high-level power supply control signal TX4 from the control unit 15, the power supply circuit 14 starts supplying power to the integrated circuit 3 with the input of the power supply control signal TX4 as a trigger. The power supply circuit 14 continuously supplies power to the integrated circuit 3 while receiving the high-level power supply control signal TX4 from the control unit 15. The power supply circuit 14 stops supplying power to the integrated circuit 3 when the level of the power supply control signal TX4 input from the control unit 15 is switched from the high level to the low level. The power supply circuit 14 continuously stops the supply of power to the integrated circuit 3 while receiving the low-level power supply control signal TX4 from the control unit 15.

  The control unit 15 includes a CPU, a ROM, a RAM 17 and other circuits. A non-volatile memory 16 such as an EEPROM is connected to the control unit 15. In the control unit 15, the CPU reads out a control program stored in the ROM to the RAM 17 and executes it to control each part of the in-vehicle power supply control device 1. The RAM 17 is a volatile memory such as an SRAM (Static Ram), and stores a discharge completion flag (corresponding to a “flag” in claims), which will be described later.

  When the accessory power supply 4 is turned off (when the level of the accessory power supply detection signal TX3 input from the accessory power supply detection circuit 13 is switched from the high level to the low level), the control unit 15 supplies the power of the low level power supply control signal TX4. The output to the circuit 14 is started. The control unit 15 continuously outputs a low-level power control signal TX4 to the power supply circuit 14 while the accessory power supply 4 is off. Furthermore, the control unit 15 monitors whether or not the first time T1 has passed without the accessory power supply 4 being turned on from the timing when the output of the low-level power control signal TX4 is started, and the first time T1 has passed. In this case, the discharge completion flag stored in the RAM 17 is set to an on value (“1”).

  On the other hand, when the accessory power supply 4 is turned on (when the level of the accessory power supply detection signal TX3 input from the accessory power supply detection circuit 13 is switched from the low level to the high level), the control unit 15 sets the discharge completion flag to the on value. In this case, immediately after the accessory power supply 4 is turned on, a high-level power supply control signal TX4 is output to the power supply circuit 14 and the discharge completion flag is set to an off value (“0”). In addition, when the accessory power source 4 is turned on and the discharge completion flag is off, the control unit 15 has a high-level power source at the timing when the second time T2 has elapsed from the timing when the accessory power source 4 is turned on. The control signal TX4 is output to the power supply circuit 14.

  Hereinafter, “when the accessory power source 4 is turned on after the first time T1 has elapsed after the level of the power control signal TX4 is switched from the high level to the low level in response to the accessory power source 4 being turned off (first case). "When the accessory power supply 4 is turned on at an interval shorter than the first time T1 after the level of the power supply control signal TX4 is switched from the high level to the low level in response to the accessory power supply 4 being turned off (second case). The process of the control unit 15 relating to the output of the power control signal TX4 will be described for three cases of “when the in-vehicle battery 2 is momentarily interrupted (third case)”.

<First case>
Hereinafter, when the accessory power supply 4 is turned on after the first time T1 has elapsed after the level of the power supply control signal TX4 is switched from the high level to the low level in response to the accessory power supply 4 being turned off (first case). The processing of the control unit 15 will be described using the timing chart of FIG. 2 shows the state of the power supply voltage of the in-vehicle battery 2 (FIG. 2A), the state of the accessory power supply detection signal TX3 input from the accessory power supply detection circuit 13 by the control unit 15 (FIG. 2B), and the control unit 15 The state of the power supply control signal TX4 output to the power supply circuit 14 (FIG. 2C), the state of the power supply voltage of the integrated circuit 3 (FIG. 2D), and the value of the discharge completion flag (FIG. 2E) It is a timing chart which shows the change with progress of time of ().

  Note that the state of the power supply voltage of the integrated circuit 3 is that when the power supply is stopped from the state where power of a predetermined voltage (in this embodiment, “3.3 V”) is supplied from the power supply circuit 14, the potential is It gradually drops from 3.3V and reaches zero potential. When the potential is zero, the discharge of the charge accumulated in the capacitor of the integrated circuit 3 has been completed. When the integrated circuit 3 is activated in this state, the operation starts from the zero potential, and the integrated circuit 3 can be safely operated. Can be activated.

  In FIG. 2, at the timing TA0, the accessory power source 4 is on and the discharge completion flag is off. From this state, when the accessory power supply 4 is turned off at the timing TA1, the accessory power supply detection circuit 13 switches the level of the accessory power supply detection signal TX3 from the high level to the low level (FIG. 2B). In response to the input of the low-level accessory power supply detection signal TX3, the control unit 15 starts outputting the low-level power supply control signal TX4 at the timing TA2 (FIG. 2C).

  When the level of the power supply control signal TX4 input from the control unit 15 is switched from the high level to the low level, the power supply circuit 14 stops the supply of power to the integrated circuit 3 at the timing TA2. Along with the stop of power supply, the power supply voltage of the integrated circuit 3 gradually decreases from “3.3 V” with the timing TA2 as a starting point (FIG. 2D).

  After starting the output of the low-level power supply control signal TX4 at the timing TA2, the control unit 15 starts measuring the elapsed time from the timing TA2. Note that the control unit 15 has a clock circuit, and executes various timing processes based on a clock signal output from the clock circuit. In the first case, the accessory power source 4 is turned on after the first time T1 has elapsed after the level of the power control signal TX4 is switched from the high level to the low level in response to the accessory power source 4 being turned off. Therefore, the first time T1 elapses before the accessory power supply 4 is turned on. When the control unit 15 detects that the elapsed time from the timing TA2 becomes the first time T1, the discharge completion flag stored in the RAM 17 at the timing TA3 when the elapsed time from the timing TA2 becomes the first time T1. Is an on value (“1”) (FIG. 2E).

  The first time T1 is a time required for the power supply voltage of the integrated circuit 3 to become zero potential after the supply of power to the integrated circuit 3 is stopped (= the discharge of the charge accumulated in the capacitor is completed). ing. Therefore, when the first time T1 has elapsed from the timing TA2, the power supply voltage of the integrated circuit 3 becomes zero potential, and the discharge of the charge accumulated in the capacitor is completed (FIG. 2D). Based on this, the discharge completion flag indicates whether the first time T1 has passed without the accessory power supply 4 being turned on after the accessory power supply 4 is turned off, in other words, the integrated circuit after the accessory power supply 4 is turned off. 3 is a flag for managing whether or not the discharge of the electric charge accumulated in the capacitor is completed when the power supply voltage 3 becomes zero potential.

  When the accessory power supply 4 is turned on at a timing TA4 that is later than the timing T3, the accessory power supply detection circuit 13 switches the accessory power supply detection signal TX3 from the low level to the high level (FIG. 2B). When the high-level accessory power supply detection signal TX3 is input, the control unit 15 determines whether the discharge completion flag stored in the RAM 17 is an on value or an off value. In the first case, the discharge completion flag is an ON value at timing TA4 (FIG. 2 (E)).

  When the discharge completion flag is the on value, the control unit 15 immediately outputs the high-level power control signal TX4 to the power circuit 14 at the timing TA5 without waiting for a second time T2 (described later). (FIG. 2 (C)). Further, the control unit 15 sets the discharge completion flag to an OFF value at timing TA5 (FIG. 2 (E)). The power supply circuit 14 starts supplying power to the integrated circuit 3 when the level of the power supply control signal TX4 input from the control unit 15 is switched from the low level to the high level at the timing TA5. In accordance with the start of power supply starting from the timing TA5, the power supply voltage of the integrated circuit 3 gradually increases from the zero potential, and the integrated circuit 3 is activated (FIG. 2D).

  As described above, according to the present embodiment, when the accessory power source 4 is turned off and the accessory power source 4 is turned on after the first time T1 has passed (first case), the accessory power source 4 is turned on. Thus, the supply of power to the integrated circuit 3 is started immediately without waiting for the second time T2. In the first case, at the timing when the accessory power supply 4 is turned on, the discharge of the electric charge accumulated in the capacitor of the integrated circuit 3 has been completed. Delay in starting the load can be suppressed.

<Second case>
Hereinafter, when the accessory power supply 4 is turned on at an interval shorter than the first time T1 after the level of the power supply control signal TX4 is switched from the high level to the low level in response to the accessory power supply 4 being turned off (second case). The processing of the control unit 15 will be described using the timing chart of FIG. 3 shows the state of the power supply voltage of the in-vehicle battery 2 (FIG. 3A), the state of the accessory power supply detection signal TX3 input from the accessory power supply detection circuit 13 by the control unit 15 (FIG. 3B), and the control unit 15 State of the power supply control signal TX4 output to the power supply circuit 14 (FIG. 3C), the state of the power supply voltage of the integrated circuit 3 (FIG. 3D), and the value of the discharge completion flag (FIG. 3E) It is a timing chart which shows the change with progress of time of ().

  In FIG. 3, at the timing TB0, the accessory power supply 4 is on and the discharge completion flag is off. From this state, when the accessory power supply 4 is turned off at the timing TB1, the accessory power supply detection circuit 13 switches the accessory power supply detection signal TX3 from the high level to the low level (FIG. 3B). In response to the input of the low-level accessory power supply detection signal TX3, the control unit 15 starts outputting the low-level power supply control signal TX4 at the timing TB2 (FIG. 3C). When the level of the power supply control signal TX4 input from the control unit 15 is switched from the high level to the low level, the power supply circuit 14 stops the supply of power to the integrated circuit 3 at the timing TB2. As power supply is stopped, the power supply voltage of the integrated circuit 3 gradually decreases from “3.3 V” starting from the timing TB2 (FIG. 3D).

  After starting the output of the low-level power supply control signal TX4 at the timing TB2, the control unit 15 starts measuring the elapsed time from the timing TB2. In the second case, after the output of the low-level power control signal TX4 is started, the accessory power supply 4 is turned on at a timing TB3 before the first time T1 elapses.

  When the accessory switch is turned on at the timing TB3, the accessory power supply detection circuit 13 switches the accessory power supply detection signal TX3 from the low level to the high level (FIG. 3B). When the high-level accessory power supply detection signal TX3 is input, the control unit 15 determines whether the discharge completion flag stored in the RAM 17 is an on value or an off value. In the second case, the discharge completion flag is an off value at the timing TA3 (FIG. 3E).

  When the discharge completion flag is an off value, the control unit 15 does not switch the level of the power control signal TX4 at the timing TB3 when the high-level accessory power supply detection signal TX3 is input, and starts from the timing TB3 during the second time T2. stand by. In the second time T2, like the first time T1, after the supply of power to the integrated circuit 3 is stopped, the power supply voltage of the integrated circuit 3 becomes zero potential (= the discharge of the charge accumulated in the capacitor is completed). It's enough time for that. In the present embodiment, the value of the second time T2 is the same as the value of the first time T1.

  The control unit 15 switches the level of the power supply control signal TX4 from the low level to the high level at the timing TB4 when the second time T2 has elapsed from the timing TB3 (FIG. 3C). The power supply circuit 14 starts supplying power to the integrated circuit 3 when the level of the power supply control signal TX4 input from the control unit 15 is switched from the low level to the high level at the timing TB4. In response to the start of power supply, the power supply voltage of the integrated circuit 3 gradually increases from zero potential, and the integrated circuit 3 is activated (FIG. 3D).

  As described above, according to the present embodiment, after the accessory power supply 4 is turned off, when the accessory power supply 4 is turned on at an interval shorter than the first time T1 (second case), the standby for the second time T2 is performed. Time is generated and the discharge of the charge accumulated in the capacitor of the integrated circuit 3 during this waiting time is completed. Due to such a configuration, even if the accessory power supply 4 is switched off / on for a very short time, the discharge of the charge accumulated in the capacitor is not completed, and the integrated circuit 3 is It is possible to reliably prevent restarting from the intermediate potential.

<Third case>
Hereinafter, the processing of the control unit 15 when the in-vehicle battery 2 is momentarily interrupted (third case) will be described with reference to the timing chart of FIG. 4 shows the state of the power supply voltage of the in-vehicle battery 2 (FIG. 4A), the state of the battery detection signal TX1 input from the battery detection circuit 10 by the control unit 15 (FIG. 4B), and the state of the constant power supply circuit 11 The state of the power supply voltage (FIG. 4C), the state of the reset control signal TX2 input from the reset signal generation circuit 12 by the control unit 15 (FIG. 4D), and the control unit 15 input from the accessory power supply detection circuit 13 The state of the accessory power supply detection signal TX3 (FIG. 4E), the state of the power supply control signal TX4 output from the control unit 15 to the power supply circuit 14 (FIG. 4F), and the state of the power supply voltage of the integrated circuit 3 (FIG. 4). (G)) and a change in the value of the discharge completion flag (FIG. 4 (H)) with time.

  In FIG. 4, at timing TC0, power is normally supplied from the in-vehicle battery 2, the accessory power supply 4 is on, and the discharge completion flag is off. From this state, when a momentary disconnection of the in-vehicle battery 2 occurs at the timing TC1, the power supply voltage of the in-vehicle battery 2 decreases at a stretch (FIG. 4A).

  As the power supply voltage of the in-vehicle battery 2 decreases at the timing TC1, the level of the battery detection signal TX1 output from the battery detection circuit 10 is switched from the high level to the low level (FIG. 4B). Further, the power supply voltage of the constant power supply circuit 11 decreases starting from the timing TC1 (FIG. 4C). Further, the level of the reset control signal TX2 output from the reset signal generation circuit 12 is switched from the high level to the low level at the timing TC1 (FIG. 4D). Further, the level of the accessory power supply detection signal TX3 output from the accessory power supply detection circuit 13 is switched from the high level to the low level at the timing TC1 (FIG. 4E). This is because the power supply voltage of the accessory power supply 4 decreases as the in-vehicle battery 2 is momentarily interrupted.

  Further, since the control unit 15 is reset with the timing TC1 as a starting point, the level of the power control signal TX4 output from the control unit 15 is switched from the high level to the low level at the timing TC1 (FIG. 4F). When the level of the power control signal TX4 input from the control unit 15 is switched from the high level to the low level, the power supply circuit 14 stops the supply of power to the integrated circuit 3 at the timing TC1. With the stop of power supply, the power supply voltage of the integrated circuit 3 gradually decreases from “3.3 V” starting from the timing TC1 (FIG. 4G). Further, the RAM 17 of the volatile memory is reset along with the reset of the control unit 15, and the value of the discharge completion flag stored in the RAM 17 becomes indefinite at the timing TC1 (FIG. 4 (H)).

  When the instantaneous interruption ends at the timing TC2, the power supply voltage of the in-vehicle battery 2 gradually increases (FIG. 4A). As the power supply voltage of the in-vehicle battery 2 increases, the power supply voltage of the constant power supply circuit 11 gradually increases starting from the timing TC2 (FIG. 4C).

  When the power supply voltage of the constant power supply circuit 11 recovers to a predetermined voltage at timing TC3, the reset signal generation circuit 12 outputs a high-level reset control signal TX2 to the control unit 15 at timing TC3 (FIG. 4D). In response to the input of the high level reset control signal TX2, the reset of the control unit 15 is released and the control unit 15 is activated. In response to the activation of the control unit 15, the reset of the RAM 17 is also released at the timing TC3. At this time, the value of the discharge completion flag stored in the RAM 17 is cleared to an initial value and becomes an off value (FIG. 4 (H)).

  When the power supply voltage of the in-vehicle battery 2 recovers to the threshold value used by the battery detection circuit 10 at the timing TC4, the battery detection circuit 10 outputs a high level battery detection signal TX1 to the control unit 15 (FIG. 4B). . Further, the power supply voltage of the accessory power supply 4 is also recovered, and the accessory power supply detection circuit 13 outputs a high-level accessory power supply detection signal TX3 to the control unit 15 at the timing TC4 (FIG. 4E). When the high-level accessory power supply detection signal TX3 is input at the timing TC4, the control unit 15 determines whether the discharge completion flag stored in the RAM 17 is an on value or an off value. In the third case, the discharge completion flag is an off value at timing TC4 (FIG. 4H).

  When the discharge completion flag is an off value, the control unit 15 does not switch the level of the power control signal TX4 at the timing TC4 when the high-level accessory power supply detection signal TX3 is input, and starts from the timing TC4 for the second time T2. stand by. The control unit 15 outputs a high-level power supply control signal TX4 to the power supply circuit 14 at the timing TC5 when the second time T2 has elapsed from the timing TC4 (FIG. 4F). The power supply circuit 14 starts supplying power to the integrated circuit 3 when the level of the power supply control signal TX4 input from the control unit 15 is switched from the low level to the high level at the timing TC5. In accordance with the start of power supply, the power supply voltage of the integrated circuit 3 gradually increases from zero potential, and the integrated circuit 3 is activated (FIG. 4G).

  As described above, according to the present embodiment, when an instantaneous interruption of the in-vehicle battery 2 occurs, the discharge completion flag stored in the RAM 17 is turned off when the reset of the control unit 15 accompanying the instantaneous interruption is released. It becomes a value, and the waiting time of the second time T2 always occurs. For this reason, even when a momentary interruption of the in-vehicle battery 2 occurs, it is possible to reliably prevent the integrated circuit 3 from being restarted from the intermediate potential without discharging the charge accumulated in the capacitor. .

  The embodiment of the present invention has been described above, but the above embodiment is merely an example of the implementation of the present invention, and the technical scope of the present invention is interpreted in a limited manner. It must not be. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

  For example, in the above-described embodiment, the low level and the high level of the power control signal TX4 output from the control unit 15 may be reversed, and the power supply signal TX4 and the power supply period are not continuously supplied. Instead of outputting a signal of a specific level, it may be configured to output a pulse signal at the start point and end point of each period. The same applies to other circuits.

  In the above embodiment, the ON value (“1”) among the values of the discharge completion flag is “specific value indicating that the first time has passed without the accessory power supply 4 being turned on” in the claims. Met. However, the on value and the off value may be reversed. In this case, the off value (“0”) is the “specific value indicating that the first time has passed without the accessory power supply 4 being turned on” in the claims.

DESCRIPTION OF SYMBOLS 1 In-vehicle power supply control device 2 In-vehicle battery 3 Integrated circuit (load)
4 Accessory power supply 14 Power supply circuit 15 Control unit

Claims (3)

A control unit for controlling the power supply circuit based on the accessory power supply;
Based on the control from the control unit, the power supply circuit for controlling the start and stop of the supply of power to the load based on the power supplied from the in-vehicle battery, and
The control unit is
When the accessory power supply is turned off, the power supply circuit is controlled to stop the supply of power to the load, and the first time elapses without the accessory power supply being turned on from the timing of the power supply stop. If the value of the flag stored in the memory is a specific value indicating that the first time has passed without the accessory power supply being turned on,
When the accessory power is turned on,
When the value of the flag is the specific value, the power supply circuit is controlled to start supplying power to the load in response to turning on the accessory power supply, and the flag is set to a value different from the specific value.
When the value of the flag is not the specific value, the power supply circuit is controlled to start supplying power to the load at a timing when a second time has elapsed from the timing when the accessory power supply is turned on. In-vehicle power supply control device.   The in-vehicle power supply control device according to claim 1, wherein the first time value and the second time value are the same.   The in-vehicle power supply control device according to claim 1, wherein the load is an integrated circuit that controls a device provided in a vehicle.