JPH0614587A - High load drive circuit - Google Patents

Abstract

(57) [Abstract] [Object] An object of the present invention is to prevent a current from flowing to an output drive circuit or the like during standby by a simple circuit configuration without requiring a dedicated circuit or signal, thereby preventing a decrease in battery capacity. A high load drive circuit capable of performing the above is provided. [Composition] The OR circuit detects the logic of the input signals IN1 and IN2, and when these input signals IN1 and IN2 indicate that the motor 22 is in the standby mode, the operation of the constant voltage circuit 25 is stopped and the constant voltage circuit 25 is stopped. The power supply from the circuit 25 to the control logic circuit 15 and the output drive circuit 16 is stopped. Therefore, it is possible to prevent the capacity of the battery from decreasing with a simple circuit configuration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high load drive circuit for driving a high load having a large current capacity such as a motor and a solenoid mounted on a vehicle.

[0002]

As is well known, a drive circuit for driving a high load having a large current capacity such as a motor mounted on a vehicle is
It drives a large current of several amps. In such a drive circuit that drives a large current, a current of several mA to several tens of mA constantly flows even when the motor is stopped or in standby (hereinafter referred to as standby). Therefore, since there is a possibility that the voltage of the battery mounted on the vehicle may be lowered, a relay is added to the power line of the drive circuit to prevent current from flowing in the drive circuit when the motor is on standby. The power supply to the drive circuit was shut off.

[0003]

However, in such a case, a relay is required in addition to the drive circuit, and
In order to control this relay, a circuit for detecting the standby time of the motor and generating a control signal is separately required, which complicates the circuit configuration.

The present invention has been made in order to solve the above problems, and an object of the present invention is to cut off a current flowing in a standby state with a simple circuit configuration without separately requiring a dedicated circuit or a signal. It is intended to provide a high load drive circuit capable of performing the above.

[0005]

In order to solve the above problems, the present invention provides a drive circuit for driving a high load having a large current capacity according to an input signal, and a power supply for supplying power from a battery to the drive circuit. Circuit, and circuit means for stopping the power supply from the power supply circuit to the drive circuit when the input signal is supplied and the level of the input signal indicates to put the high load in the standby mode. ing. The power supply circuit is composed of a constant voltage circuit. Furthermore, the input signal is a logic signal,
The circuit means is composed of a logic circuit.

[0006]

That is, the present invention detects the logic of the input signal by the circuit means including the logic circuit, and when this input signal indicates that the high load is in the standby mode, the power supply from the power supply circuit to the drive circuit is provided. Supply is stopped. Therefore, since a dedicated circuit or signal is not required separately, the power supply to the drive circuit can be stopped with a simple circuit configuration.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a case where the present invention is applied to a drive circuit for driving a motor mounted on a vehicle.

In FIG. 1, input signals IN1 and IN2 are supplied to signal input terminals 11 and 12. These signal input terminals 11 and 12 are connected to the input terminals of the control logic circuit 15 via the buffer circuits 13 and 14. As shown in FIG. 2, the control logic circuit 15 generates a signal for setting the operating state of the motor according to the logic level of the input signal. The output signal of the control logic circuit 15 is an output drive circuit. 1
6 is supplied. The output drive circuit 16 generates a control signal for a transistor that drives a motor according to the output signal of the control logic circuit 15. The output signal of the output drive circuit 16 is the transistor 1
Supplied to bases 7, 18, 19, 20 respectively.
The collectors of the transistors 17 and 18 are power supply terminals (V
cc) 21 and the emitters of these transistors 17 and 18 are connected to one end and the other end of the motor 22, respectively. The collectors of the transistors 19 and 20 are connected to one end and the other end of the motor 22, respectively. The emitters of these transistors 19 and 20 are connected to the ground terminal 23 together with the ground terminals of the control logic circuit 15 and the output drive circuit 16. A battery BT is connected to the power supply terminal 21 and the ground terminal 23.

On the other hand, the output terminals of the buffer circuits 13 and 14 are connected to the input terminal of the OR circuit 24. The output terminal of the OR circuit 25 is connected to one input terminal of the constant voltage circuit 25. The other input end of the constant voltage circuit 25 is connected to the power supply terminal 21, and the output terminal is connected to the power supply terminals of the control logic circuit 15 and the output drive circuit 16. The constant voltage circuit 26 is applied to the control logic circuit 15 and the output drive circuit 16 except when both the input signals IN1 and IN2 are at low level (L) (standby mode, that is, stop mode in which the output is high impedance). A voltage is supplied to stop the supply of the constant voltage to the control logic circuit 15 and the output drive circuit 16 in the standby mode in which both the input signals IN1 and IN2 are at the low level. Therefore, the output signals of the control logic circuit 15 and the output drive circuit 16 are all turned off,
Control logic circuit 15, output drive circuit 1
6, transistors 17, 18, 19, 20, motor 22
No current flows through. FIG. 3 shows the buffer circuit 13,
14, an OR circuit 24, and a constant voltage circuit 25 are shown as an example, and the same portions are denoted by the same reference numerals.

The signal input terminal 11 is connected to one end of a resistor 13a forming the buffer circuit 13. This resistor 13
The other end of a is connected to the base of the transistor 13b and is also connected to the emitter of the transistor 13b via the resistor 13c. Further, the signal input terminal 12 is connected to one end of a resistor 14 a that constitutes the buffer circuit 14. The other end of the resistor 14a is connected to the base of the transistor 14b and is also connected to the emitter of the transistor 14b via the resistor 14c. The collectors of these transistors 13b and 14b are diodes 31, 3
2 through the control logic circuit 15 in the reverse direction.
Of the transistors 35 and 36 via resistors 33 and 34, respectively. These transistors 3
The emitters of the reference numerals 5 and 36 are connected to the power supply terminal 21, and the second collectors thereof are connected to the anodes of the diodes 24a and 24b forming the OR circuit 24, respectively.
The cathodes of these diodes 24a and 24b are connected to the base of a transistor 25a that constitutes the constant voltage circuit 25. The collector of the transistor 25a is connected to the power supply terminal 21, the emitter is connected to the power supply terminals of the control logic circuit 15 and the output drive circuit 16, and the transistor 25a is connected via the resistor 25b.
Connected to the base of. The base of the transistor 25a is connected to the ground terminal 23 via the Zener diode 25c.

In the above structure, the input signals IN1 and IN
When at least one of 2 is at the high level, at least one of the transistors 13b and 14b of the buffer circuits 13 and 14 becomes conductive. The control logic circuit 15 operates as described above according to the conduction state of the transistors 13b and 14b. At this time, at least one of the transistors 35 and 36 becomes conductive, so that at least one of the diodes 24a and 24b forming the OR circuit 25 becomes conductive and the Zener diode 25c forming the constant voltage circuit 25 is biased. Therefore, a constant current corresponding to the output voltage of the Zener diode 25c is output from the emitter of the transistor 25a that constitutes the constant voltage circuit 25, and this constant current is the control logic circuit 15
And to the output drive circuit 16.

On the other hand, when both the input signals IN1 and IN2 are at the low level, the transistors 13b and 14b of the buffer circuits 13 and 14 are all non-conductive. Therefore, the input end of the control logic circuit 15 has a high impedance, and the output logic is in the standby mode. At this time, the transistors 35 and 36 are both non-conductive, so that the diodes 24a and 24b forming the OR circuit 25 are both non-conductive. Therefore, the Zener diode 25c and the transistor 25a are turned off, so that the control logic circuit 15 and the output drive circuit 16 are not supplied with power.

According to the above embodiment, the logical level of the input signal is detected by the OR circuit 25, and the operation of the constant voltage circuit 25 is stopped when the output of the OR circuit 25 is low level, that is, in the standby mode. However, the power supplies to the control logic circuit 15 and the output drive circuit 16 are stopped. Therefore, in the standby mode, no current flows through the control logic circuit 15 and the output drive circuit 16, so that the battery B
The voltage drop of T can be prevented.

In the standby mode, the OR circuit 25
Can be detected by detecting the logic level of the input signal, and the output signal of the OR circuit 25 controls the operation of the transistor 25a forming the constant voltage circuit 25. Therefore, the battery BT has a simpler structure than the conventional one. It is possible to prevent the voltage drop.

In the above embodiment, the case where the present invention is applied to the motor has been described, but the present invention is not limited to this, and the present invention can be applied to a high load such as a solenoid.

In the above embodiment, the logic of the input signal is detected by the OR circuit, but the present invention is not limited to this, and a circuit according to the logic set in the control logic circuit may be used. Besides, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the invention.

[0017]

As described above in detail, according to the present invention,
It is possible to provide a high load drive circuit capable of interrupting a current flowing during standby by a simple circuit configuration without requiring a dedicated circuit or a signal and capable of preventing a decrease in battery capacity.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing the logic of an input signal of the circuit shown in FIG.

FIG. 3 is a circuit diagram specifically showing the circuit shown in FIG.

[Description of Reference Signs] 15 ... Control logic circuit, 16 ... Output drive circuit, 22 ... Motor, 24 ... OR circuit, 25 ... Constant voltage circuit, IN1, IN2 ... Input signal, BT ... Battery

Claims (3)

[Claims] 1. A drive circuit for driving a high load having a large current capacity according to an input signal, a power supply circuit for supplying power from a battery to the drive circuit, and a level of the input signal supplied with the input signal. When it indicates that the high load is in a standby mode, circuit means for stopping the power supply from the power supply circuit to the drive circuit, and a high load drive circuit. 2. The high load drive circuit according to claim 1, wherein the power supply circuit is a constant voltage circuit. 3. The high load drive circuit according to claim 1, wherein the input signal is a logic signal, and the circuit means is a logic circuit.