JP2011233100A - Power source circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source circuit capable of connecting of plural types of batteries having different rated output voltages to reduce number of component types (components) and man-hours to be managed.SOLUTION: An on-vehicle shared power source circuit 16 comprises an input unit to which one of plural types of batteries with mutually different rated output voltages is connected and an output unit having a constant-voltage circuit to which an on-vehicle apparatus body which makes up an on-vehicle apparatus is connected. The on-vehicle shared power source circuit 16 further comprises a power conversion circuit 23 which supplies, when a battery with a lowest rated output voltage is connected, supply a voltage from the battery to the constant-voltage circuit as it is, and supplies, when a battery with a higher rated output voltage is connected, power to the constant-voltage circuit after performing power conversion so that the power should not surpass power durability of a transistor.

Description

  The present invention relates to a power supply circuit, and more particularly to a power supply circuit for supplying electric power from a battery mounted on a vehicle to an in-vehicle device.

2. Description of the Related Art Conventionally, there is known a power supply circuit that is connected to an in-vehicle battery mounted on a vehicle as a power source and supplies stabilized power to each part of the on-vehicle device mounted on the on-vehicle device (see, for example, Patent Document 1). ).
By the way, as an in-vehicle battery, there are a plurality of types of batteries such as a battery having a rated output voltage of 24V (for a large vehicle such as a dump truck), a rated output voltage of 12V (for a normal passenger car), and a rated output voltage of 6V (for a motorcycle). .
For this reason, when manufacturing a vehicle-mounted device (such as a car navigation device or a car audio device), the vehicle-mounted device is separately manufactured according to the rated output voltage of the vehicle-mounted battery of the vehicle on which the vehicle-mounted device is mounted. It was.

JP 2005-313725 A

On the other hand, in-vehicle devices are equipped with a plurality of constant voltage circuits that supply a constant voltage to each part, and in order to make them separately for each battery, transistors and capacitors that make up the constant voltage circuit are connected. It is necessary to prepare a plurality of types corresponding to the rated output voltage of the battery, which increases the number of parts to be managed and increases the man-hours for management.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a power supply circuit that can connect a plurality of types of batteries having different rated output voltages, and thus can reduce the types of components (number of components) to be managed and the management man-hours. There is.

  In order to solve the above-described problem, a first aspect of the present invention is that an in-vehicle device main body that configures an in-vehicle device in any one of a plurality of types of batteries having different rated output voltages is connected to the input unit. An in-vehicle power supply circuit to be connected, wherein the in-vehicle device body includes a constant voltage circuit having a voltage conversion transistor and a capacitor, and the transistor and the capacitor are any of the plurality of types of batteries. However, when a voltage within the allowable voltage range can be applied and the battery with the lowest rated output voltage is connected, the power supplied from the battery is supplied to the constant voltage circuit as it is, When a battery with a higher rated output voltage than a battery with a lower rated output voltage is connected, power conversion is performed so that the power resistance of the transistor is not exceeded. Performed and further comprising a power converter circuit for supplying power to the constant voltage circuit from.

  According to the above configuration, when a battery with the lowest rated output voltage is connected, the power conversion circuit supplies the power supplied from the battery as it is to the constant voltage circuit, so that the power conversion circuit is more powerful than the battery with the lowest rated output voltage. When a battery with a high rated output voltage is connected, power conversion is performed so that the power resistance of the transistor is not exceeded, and then power is supplied to the constant voltage circuit. Even when one of these is connected, it can be shared with the one corresponding to the case where the battery with the lowest rated output voltage of the transistor is connected. Points) and management man-hours can be reduced.

According to a second aspect of the present invention, in the first aspect, when the battery having a higher rated output voltage than the battery having the lowest rated output voltage is connected, the power conversion circuit is configured to And a power consuming circuit that supplies the constant voltage circuit after consuming a part.
According to the above configuration, when a battery having a higher rated output voltage than a battery having the lowest rated output voltage is connected, the power consuming circuit consumes a part of the power supplied from the battery and then becomes a constant voltage circuit. As a result, power is supplied to the transistors constituting the constant voltage circuit according to the withstand power of the transistor, and the transistor is reliably protected, and the constant voltage is stably supplied from the constant voltage circuit having the transistor and the capacitor. Therefore, the vehicle-mounted device body can be operated stably.

According to a third aspect of the present invention, in the second aspect, the power conversion circuit includes an input voltage detection circuit that detects an input voltage from the battery, and based on the input voltage detected by the input voltage detection circuit, When a battery having a higher rated output voltage than the battery having the lowest rated output voltage is connected, the power consumption circuit is interposed between the constant voltage circuit and the battery.
According to the above configuration, the input voltage detection circuit detects the input voltage from the battery, and the power conversion circuit is rated more than the battery with the lowest rated output voltage based on the input voltage detected by the input voltage detection circuit. When a battery with a high output voltage is connected, the power consumption circuit is inserted between the constant voltage circuit and the battery, so that the power supplied to the transistor takes into account the withstand power of the transistor and is reliable. Thus, the transistor can be protected, and as a result, a constant voltage can be supplied stably.

According to a fourth aspect of the present invention, in any one of the first aspect to the third aspect, the in-vehicle device body is a controller that controls the constant voltage circuit by supplying power from the battery via a vehicle accessory switch. The power conversion circuit is characterized in that, when the constant voltage circuit becomes operable under the control of the controller, power supply to the constant voltage circuit is started.
According to the above configuration, when power is supplied to the controller from the battery via the accessory switch of the vehicle and the constant voltage circuit becomes operable under the control of the controller, power supply to the constant voltage circuit is started. Therefore, the constant voltage can be reliably output to the constant voltage circuit.

  According to the present invention, components such as transistors can be made common regardless of the rated output voltage of the battery that connects the components such as transistors used in the constant voltage circuit constituting the vehicle-mounted device, There is an effect that the types of parts (number of parts) to be managed and the man-hours for management can be reduced.

It is a general | schematic block diagram of the vehicle-mounted system of embodiment. It is explanatory drawing of the circuit structural example of a constant voltage circuit. It is explanatory drawing of the use voltage range of the transistor and capacitor | condenser used for a constant voltage circuit. It is a general | schematic block diagram of a common power supply circuit. It is explanatory drawing of the detailed circuit structure of a shared power supply circuit. It is a general | schematic block diagram of the vehicle-mounted system of embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration block diagram of an in-vehicle system according to an embodiment.
The in-vehicle system 10 is roughly divided into an in-vehicle battery 11 that supplies electric power, an in-vehicle device 12 that operates by receiving electric power supply from the in-vehicle battery 11 via the first input terminal TIN1, and the electric power from the in-vehicle battery 11 And an accessory (ACC) switch 14 that supplies the vehicle-mounted device 12 via a two-input terminal TIN2.
The in-vehicle device 12 converts the electric power supplied from the in-vehicle device main body 15 and the in-vehicle battery 11 through the first input terminal TIN1 into electric power suitable for the in-vehicle device main body 15, and converts the electric power suitable for the in-vehicle device main body 15 through the output terminal TOUT1. And a common power supply circuit 16 that supplies power to the power supply 15.

The in-vehicle device body 15 is supplied with electric power directly from the in-vehicle battery 11 via the second input terminal TIN2 when the plurality of constant voltage circuits 17-1, 17-2 and the accessory switch 14 are turned on. And a power supply controller 18 for controlling the constant voltage circuits 17-1 and 17-2.
Here, the common power supply circuit 16 has a plurality of constant voltage circuits 17-1, 17-of the vehicle-mounted device main body 15 regardless of whether the battery with the rated output voltage 12 V or the battery with the rated output voltage 24 V is connected as the vehicle-mounted battery 11. Power conversion is performed as necessary so that 2 can operate, and power is supplied to the constant voltage circuits 17-1 and 17-2. The constant voltage circuits 17-1 and 17-2 are also shared power supply circuits. 16 is operable in both the power range and the voltage range supplied from 16.
The allowable output voltage range of the in-vehicle battery 11 connected to the common power supply circuit 16 is 10.8 V (minimum allowable voltage) to 16 V (maximum allowable voltage) when a battery with a rated output voltage of 12 V is assumed as the in-vehicle battery 11. )

Moreover, the allowable output voltage range when a battery with a rated output voltage of 24 V is assumed as the in-vehicle battery 11 is 16 V (minimum allowable voltage) to 31.2 V (maximum allowable voltage).
When the constant voltage circuits 17-1 and 17-2 are configured so that the rated output voltage of the in-vehicle battery 11 can be shared between 12V and 24V, the constant voltage circuits 17-1 and 17-2 are configured. The specifications (characteristics) required for the transistors and capacitors differ even in the same constant voltage circuit.
This is because the transistor is a component having relatively high withstand voltage (for example, with a withstand voltage of 50V in the 12V specification), and on the other hand, it requires a withstand power. In other words, even if the applied voltage is within the allowable voltage range, the transistor may break beyond its withstand power if the input current is large.

In addition, since the capacitor is a component having a relatively low withstand voltage, it is necessary to have a specification that can withstand a maximum allowable voltage.
As described above, if a battery having a rated output voltage of 12 V or 24 V is connected as the on-vehicle battery 11 to be connected, the voltage range input to the shared power supply circuit 16 is, for example, 10.8 V to 31.2 V Become.
Here, the configuration of the constant voltage circuits 17-1 and 17-2 will be described.

FIG. 2 is an explanatory diagram of a circuit configuration example of the constant voltage circuit.
Since the basic circuit configurations of the constant voltage circuits 17-1 and 17-2 are the same, the constant voltage circuit 17-1 will be described as an example.
The constant voltage circuit 17-1 is a voltage dividing resistor that constitutes a voltage dividing circuit that divides the voltage input from the output terminal TOUT1 of the common power supply circuit 16 and applies it to the collector C of the transistor Q1. A Zener diode ZD2 that becomes conductive when the voltage after being stepped down by R11, R12 and the voltage dividing resistors R11, R12 exceeds the Zener voltage is connected in parallel to the Zener diode ZD2, and the switching noise of the Zener diode ZD2 is removed. Electrolytic capacitor EC2 and capacitor CC, and a backflow prevention diode D4.

Next, the constant voltage supply operation of the constant voltage circuit 17-1 will be described.
When the voltage applied from the output terminal TOUT1 of the common power supply circuit 16 of the constant voltage circuit 17-1 to the Zener diode ZD2 via the voltage dividing resistors R11 and R12 exceeds the Zener voltage of the Zener diode ZD2, The diode ZD2 becomes conductive. At this time, noise accompanying switching of the Zener diode ZD2 becomes a high-frequency component, and therefore flows to the ground side through the electrolytic capacitor EC2 and the capacitor CC2, and is removed.
In this case, if the current flowing through the voltage dividing resistor R2 is small, the voltage drop in the voltage dividing resistor R2 is reduced, the base potential of the transistor Q1 is secured, and the collector C-emitter of the transistor Q1 is secured. Since the voltage drop between E becomes small, the output voltage of the transistor Q1 rises.

On the other hand, if the current flowing through the voltage dividing resistor R2 is large, the voltage drop of the voltage dividing resistor R2 increases, the base potential of the transistor Q1 decreases, and the voltage drop between the collector C and the emitter E of the transistor Q1 increases. The output voltage of the transistor Q1 will drop.
At this time, since the current flowing through the resistor R2 is equal to the current flowing through the Zener diode ZD2, the voltage applied to the output terminal TOUT1 of the shared power supply circuit 16 increases as the voltage applied to the output terminal TOUT1 of the shared power supply circuit 16 increases. If the applied voltage is low, it decreases.
Therefore, the voltage (output voltage) at the output terminal TOUT11 of the constant voltage circuit 17-1 is such that the voltage applied to the output terminal TOUT of the shared power supply circuit 16 is higher than the predetermined constant voltage reference voltage of the constant voltage circuit 17-1. When the voltage is higher, the voltage decreases, and when the voltage applied to the output terminal TOUT of the common power supply circuit 16 is lower than the predetermined constant voltage reference voltage of the constant voltage circuit 17-1, the voltage increases and is maintained at a constant voltage. .

FIG. 3 is an explanatory diagram of the operating voltage range of transistors and capacitors used in the constant voltage circuit.
First, the allowable voltage range of a battery with a rated output voltage of 12 V is 10.8 V (minimum allowable voltage) to 16 V (maximum allowable voltage) as shown in FIG.
Further, the allowable voltage range of the battery with the rated output voltage of 24V is 16V (minimum allowable voltage) to 31.2V (maximum allowable voltage) as shown in FIG.
As the voltage conversion transistors constituting the constant voltage circuits 17-1 and 17-2, when a transistor with a rated output voltage of 12V is used from the viewpoint of component size and cost, the withstand voltage of the transistor is simply shown in FIG. As shown in 3 (c), the range of 10.8 to 31.2V is covered, and there is no problem even if a battery with a rated output voltage of 24V is used.
However, in the actual use of the transistor, it is necessary to consider not only the withstand voltage but also the withstand voltage of the transistor. As an actual use voltage range in consideration of the withstand power, for example, as shown in FIG. Furthermore, the voltage range is less than 24V from 10.8V, which is the lowest allowable voltage of the in-vehicle battery 11 with the rated output voltage of 12V.

On the other hand, with regard to the electric field capacitor EC2 and the capacitor CC2 (particularly the capacitor CC2) constituting the constant voltage circuits 17-1 and 17-2, the withstand voltage is more problematic than the withstand power. That is, since the withstand voltage is lower than that of a power conversion transistor, it is preferable to use a 24V specification in terms of withstand voltage. Therefore, as shown in FIG. 3 (e), the usable voltage range in the normal specification capacitor of 24V is the maximum allowable voltage of 31.2V or less of the on-vehicle battery 11 with the rated output voltage of 24V, that is, the on-vehicle of the rated output voltage of 12V. The minimum allowable voltage of the battery 11 is 10.8 V or more and 31.2 V.
That is, in the case of the above configuration, the voltage range that the common power supply circuit 16 can supply to the constant voltage circuits 17-1 and 17-2 is rated output when a battery with a rated output voltage of 12 V is connected as the in-vehicle battery 11. Since the constant voltage circuits 17-1 and 17-2 can operate in the entire allowable output voltage range of the battery having the voltage of 12V, the allowable output voltage range (10.8 to 16V) of the battery having the rated output voltage of 12V is used as it is. That's fine.

On the other hand, when a battery having a rated output voltage of 24 V is connected as the in-vehicle battery 11, the capacitors constituting the constant voltage circuits 17-1 and 17-2 can operate in the entire output voltage range. Is set to 16 V, which is the minimum allowable voltage of the on-vehicle battery having a rated output voltage of 24 V, and the maximum allowable voltage may be output so as to be the maximum allowable voltage (for example, less than 24 V) determined from the power resistance of the transistor.
In summary, the common power supply circuit 16 in the present embodiment outputs the output voltage of the in-vehicle battery 11 to the constant voltage circuits 17-1 and 17-2 as it is when the in-vehicle battery 11 has a rated output voltage of 12V. When the in-vehicle battery 11 has a rated output voltage of 24 V, the maximum allowable voltage (in this embodiment, the output voltage of the in-vehicle battery 11 is determined from the withstand power of the transistors constituting the constant voltage circuits 17-1 and 17-2. It is sufficient to operate so as to be less than 24V).

FIG. 4 is a schematic configuration block diagram of the shared power supply circuit.
The shared power supply circuit 16 is roughly classified into an input voltage detection circuit 21 that outputs an output switching control signal S when it is detected that the rated output voltage of the in-vehicle battery 11 connected to the first input terminal TIN1 is 24V. When the output switching control signal S is not input from the input voltage detection circuit 21, the in-vehicle battery 11 is a battery having a rated output voltage of 12V. Therefore, the output voltage of the in-vehicle battery 11 is output as it is, and the input voltage detection circuit In the state in which the output switching control signal S is input from 21, the in-vehicle battery 11 is a battery having a rated output voltage of 24V, so that the power consumption circuit 22 built in consumes the output power of the in-vehicle battery 11. Transistors constituting the constant voltage circuits 17-1 and 17-2 via the output terminal TOUT1 (transistors in this embodiment) And a, a power converter circuit 23 supplies electric power corresponding to the power handling capability of Q1).

FIG. 5 is an explanatory diagram of a detailed circuit configuration of the shared power supply circuit.
The input voltage detection circuit 21 includes a PNP transistor Q11 whose emitter E is connected to the first input terminal TIN1, and an emitter E-base of the transistor Q11 when the voltage applied to the first input terminal TIN1 drops. The maximum allowable voltage when the diode D1 for maintaining the transistor Q11 in an OFF state with the B connected in a short-circuit state and the anode connected to the ground GND and the voltage of the first input terminal TIN1 being the rated output voltage 12V of the in-vehicle battery 11 (Zener diode ZD1 that becomes conductive when exceeding 16V in the present embodiment) and a voltage dividing circuit that divides the voltage applied to the first input terminal TIN1 when the Zener diode ZD is conductive Voltage dividing resistors R1 and R2.

  On the other hand, in the power conversion circuit 23, the transistor Q12 whose collector C is connected to the output terminal TOUT1, the backflow prevention diodes D2 and D3, and the in-vehicle battery 11 connected to the first input terminal TIN1 is a battery with a rated output of 24V. The power consumption resistor R3 for consuming power and outputting the output voltage from the output terminal TOUT1 as a voltage lower than the maximum allowable voltage of the transistors constituting the constant voltage circuits 17-1 and 17-2, and the input voltage. When the output switching control signal S is input from the detection circuit 21, the voltage dividing resistors R4, R5, R6 for applying a voltage for turning off the transistor Q12 between the emitter E and base B of the transistor Q12. And an electrolytic capacitor EC1 and a capacitor CC1 connected in parallel between the output terminal TOUT and the ground GND. And a, a smoothing circuit SM for performing smoothing operation for removing such noise on the supply signal output from the output terminal TOUT.

Next, the operation of the shared power supply circuit will be described.
First, the operation when a battery with a rated output voltage of 24 V is connected as the in-vehicle battery 11 will be described.
When the accessory switch 14 is turned on by the driver, the power controller 18 of the in-vehicle device body 15 is supplied with power from the battery 11 via the second input terminal TIN2.
As a result, the power supply controller 18 has the constant voltage circuits 17-1 and 17-2 from the common power supply circuit 16 when the constant voltage circuits 17-1 and 17-2 become operable under the control of the power supply controller 18. 2 is started to supply power. Specifically, power is not supplied by, for example, providing a switch before the output terminal TOUT1 of the shared power supply circuit 16. Alternatively, a switch is provided on the input side of the constant voltage circuits 17-1 and 17-2 so that the power supply from the shared power supply circuit 16 is cut off.

And the battery of the rated output voltage 24V is connected as the vehicle-mounted battery 11, the power supply to the constant voltage circuits 17-1 and 17-2 is started under the control of the power supply controller 18, and the voltage is normally supplied. In this case, since a voltage exceeding the Zener voltage of the Zener diode ZD1 is applied, the Zener diode ZD1 becomes conductive, and a constant voltage is applied between the cathode and the anode of the Zener diode ZD1. .
As a result, a current also flows between the emitter E and base B of the transistor Q11, and the transistor Q11 is turned on. That is, the transistor Q11 outputs the output switching control signal S to the power conversion circuit 23 via the collector C when a battery having a rated output voltage of 24V is connected as the in-vehicle battery 11.

When the output switching control signal S is input to the power conversion circuit 23 and the voltage across the resistor R6 increases, the voltage between the emitter E and the base of the transistor Q12 of the power conversion circuit 23 decreases, and the transistor Q12 is in the open state ( Off state).
As a result, the current supplied from the first input terminal TIN1 flows through the resistor R3 as the power consuming circuit 22, and power is consumed by the resistor R3, and the voltage decreases, and the vehicle is connected to the vehicle from the output terminal TOUT1. It is supplied to the constant voltage circuits 17-1 and 17-2 of the device.

  As a result, the current after power consumption flows through the transistors constituting the constant voltage circuits 17-1 and 17-2 (in the case of the constant voltage circuit 17-1, the transistor Q1). The power (with a voltage value of less than 24V) within the withstand power range of the transistors constituting the circuit 17-2 is supplied, and the transistors can operate normally. At this time, the capacitors constituting the constant voltage circuits 17-1 and 17-2 are only applied with a voltage of 31.2 V at the maximum, and can operate normally.

Next, the operation when a battery having a rated output voltage of 12 V is connected as the in-vehicle battery 11 will be described.
When the accessory switch 14 is turned on by the driver, the power controller 18 of the in-vehicle device body 15 is supplied with power from the battery 11 via the second input terminal TIN2, and the power controller 18 is connected to the constant voltage circuit 17. -1, 17-2 at a stage where the power supply controller 18 can operate, the power supply from the shared power supply circuit 16 to the constant voltage circuits 17-1, 17-2 is started, and the in-vehicle battery 11 When the battery having the rated output voltage of 12V is connected and the output switching control signal S is not input from the input voltage detection circuit 21, the transistor Q11 is in an open state (off state), and therefore the voltage dividing resistors R4 and R5 , R6, the base voltage of the transistor Q12 decreases, the voltage between the emitter E and base B increases, and the transistor Q12 is closed. In this state, the power supplied from the first input terminal TIN1 is the same voltage via the emitter E and collector C of the transistor Q12, and the constant voltage circuits 17-1 and 17- of the in-vehicle device from the output terminal TOUT. 2 will be supplied.

  As a result, the battery voltage (10.8V to 16V) of the rated output voltage 12V is applied to the transistors constituting the constant voltage circuits 17-1 and 17-2 (in the case of the constant voltage circuit 17-1, the transistor Q1). Is applied, and power less than the withstand voltage of the transistor is sufficiently supplied, and the transistor operates normally. At this time, the capacitors constituting the constant voltage circuits 17-1 and 17-2 are only applied with a voltage of 16V at the maximum, and can operate normally.

  As described above, according to the present embodiment, any one of a plurality of types of batteries having different rated output voltages is connected to the input unit, and the in-vehicle device body constituting the in-vehicle device is connected to the output unit. In a vehicle power supply circuit that is used, components such as transistors used in constant voltage circuits that make up in-vehicle devices can be shared and managed regardless of the rated output voltage of the connected battery. The type of parts (number of parts) and management man-hours can be reduced.

The above explanation is for the case where there are two types of batteries connected to the shared power supply circuit 16, but even when there are three or more types of batteries, if the battery with the lowest rated output voltage is connected, the battery When the battery with higher rated output voltage than the battery with the lowest rated output voltage is connected, the power resistance of the power conversion transistor that constitutes the constant voltage circuit If power is converted so as not to exceed the value, and then power is supplied to the constant voltage circuit, the same application is possible.
Even when a battery with the lowest rated output voltage is connected, it is possible to perform power conversion so that it does not exceed the power resistance of the power conversion transistor that constitutes the constant voltage circuit. Since it only increases electric power, it is not preferable from the viewpoint of power consumption.

DESCRIPTION OF SYMBOLS 10 In-vehicle system 11 In-vehicle battery 12 In-vehicle device 14 Accessory switch 15 In-vehicle device main body 16 Shared power supply circuit 17-1, 17-2 Constant voltage circuit 18 Power supply controller 21 Input voltage detection circuit 22 Power consumption circuit 23 Power conversion circuit CC1, CC2 Capacitor EC1, EC2 Electrolytic capacitor Q1 Transistor R3 Power consumption resistor (power consumption circuit)

Claims (4)

An in-vehicle power supply circuit in which any one of a plurality of types of batteries having different rated output voltages is connected to an input unit, and an in-vehicle device body constituting the in-vehicle device is connected to the output unit,
The in-vehicle device body includes a constant voltage circuit having a voltage conversion transistor and a capacitor,
The transistor and the capacitor can be applied with a voltage within the allowable voltage range of any of the plurality of types of batteries.
When the battery with the lowest rated output voltage is connected, the power supplied from the battery is supplied to the constant voltage circuit as it is, and the battery with the higher rated output voltage than the battery with the lowest rated output voltage is connected. In such a case, the power supply circuit includes a power conversion circuit that performs power conversion so as not to exceed a withstand power of the transistor and then supplies power to the constant voltage circuit. The power supply circuit according to claim 1,
When the battery having a higher rated output voltage than the battery having the lowest rated output voltage is connected, the power conversion circuit consumes a part of the power supplied from the battery and then supplies the power to the constant voltage circuit. A power supply circuit comprising a power consumption circuit. The power supply circuit according to claim 2,
The power conversion circuit includes an input voltage detection circuit that detects an input voltage from the battery, and based on the input voltage detected by the input voltage detection circuit, the rated output voltage is lower than that of the battery having the lowest rated output voltage. When a battery having a high value is connected, the power consumption circuit is interposed between the constant voltage circuit and the battery.
A power supply circuit characterized by that. The power supply circuit according to any one of claims 1 to 3,
The in-vehicle device main body is supplied with power from the battery via a vehicle accessory switch, and includes a controller that controls the constant voltage circuit,
The power conversion circuit starts supplying power to the constant voltage circuit when the constant voltage circuit becomes operable under the control of the controller.
A power supply circuit characterized by that.

Images