JPH06339233A - Power source switching apparatus - Google Patents

Abstract

PURPOSE:To provide a power source switching apparatus for holding a circuit voltage against chattering of a power source due to an impact or vibration to be applied to an apparatus. CONSTITUTION:An apparatus having a main power source 1 using a battery and a booster 2 for boosting it comprises a first load circuit 3 for generating a malfunction due to a voltage drop of the power source 1, a second load circuit 4 to be driven by the booster 2, a voltage detector 5 for detecting a voltage drop when the power source is instantaneously interrupted or an instantaneous large current load occurs, and a switching circuit 6 for temporarily supplying power by the booster 2 to the circuit 3 when a voltage drop due to the detector 5 is detected. When a vibration of a short time is applied to the apparatus and the power source is instantaneously interrupted, or when an instantaneous large current load such as starting of a motor occurs, power from the booster is supplied to the first load circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit in which a battery drive represented by a portable headphone stereo device is used as a main power supply means and a plurality of different voltages are formed inside the device by using a booster circuit. The present invention relates to a power supply switching device for temporarily supplying power from a high potential system after boosting to a temporary circuit system before boosting.

[0002]

2. Description of the Related Art Conventionally, in order to prevent equipment from stopping or malfunctioning due to voltage drop during momentary large current load such as momentary stoppage caused by chattering of a power source or motor start-up, a control circuit such as a microcomputer or a memory. -The power supply system of the holding circuit has a delay circuit having a time constant composed of a voltage holding resistor and a capacitor. In this case, headphones such as stereo equipment, which is normally driven by a single battery, have low voltage, so it is necessary to increase the resistance to increase the time constant and to prevent backflow to other circuits. It is difficult to insert a capacitor, and as a result, the capacitance of the capacitor is increased.

[0003]

However, in the conventional power source holding as described above, the number of types of microcomputers has increased in recent years, or element variations due to process variations cause
The minimum voltage required for operation and memory retention is different, and some require a relatively high voltage. Therefore, for example, if the conventional 0.8V power becomes 1.0V, the capacity of the holding capacitor must be further increased, and there is a problem that the size of the device increases as the size of the capacitor increases. Was there.

In view of the above-mentioned conventional problems, the present invention has been made for the purpose of providing a power supply switching device for holding a circuit voltage against chattering of power supply generated by shock or vibration applied to equipment. is there.

[0005]

In order to solve the above problems, a power supply switching device of the present invention is a device having a main power supply supplied using a battery as a power supply and a booster circuit for boosting and supplying the main power supply voltage. In this case, the first load circuit driven directly by the main power source and causing a malfunction due to the reduction of the power source voltage, the second load circuit driven by the booster circuit, and the momentary stop of the main power source A voltage detection circuit that detects a voltage drop such as when a voltage drop occurs or when an instantaneous large current load occurs, and when the voltage drop is detected by the detection circuit, a power supply is temporarily supplied from the booster circuit to the first load circuit. And a switching circuit.

Further, in a device having a main power source supplied by using a battery as a power source and a booster circuit for boosting and supplying the main power source voltage, the main power source directly drives and resets when the power source voltage drops. A first load circuit having at least a memory, a second load circuit driven by the booster circuit, a voltage detection circuit for detecting a voltage drop of the main power supply, and a first voltage detection circuit for detecting a voltage drop by the detection circuit. A switching circuit for temporarily supplying power to the first load circuit from the booster circuit; and a delay provided on a path for supplying a reset signal to the reset input terminal of the first load circuit upon detection of a voltage drop of the voltage detection circuit. And a circuit.

[0007]

The present invention has the above-described structure, when a shock or vibration is applied to the equipment for a short time to cause a momentary stop of the main power source or an instantaneous large current load such as a motor start occurs.
By detecting the voltage drop and switching the switching circuit, it is possible to supply power from the booster circuit to the first load circuit, and to stop momentarily by chattering such as shock or vibration applied to the equipment. It is possible to hold the control circuit, the memory and the like, and the same operation is performed even when the battery voltage is suddenly changed due to a large current load such as a motor start.

Further, according to the present invention, when the voltage detection circuit detects a voltage drop, power is temporarily supplied from the booster circuit, and the first load circuit is reset after a certain delay time by the delay circuit. Therefore, when the voltage drops due to the exhaustion of the battery, a short-time shock or vibration is applied to the equipment to cause a momentary stop of the main power supply, or an instantaneous large current load such as motor start occurs, it is distinguished from the voltage drop. You will be able to do it.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the power supply switching device of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a conceptual diagram of a power supply switching device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a main power source composed of a battery, and 2 is a booster circuit for boosting the voltage of the main power source 1. Reference numeral 3 is a first load circuit which is normally directly driven by the main power supply 1 and causes a malfunction due to a decrease in the power supply voltage. Reference numeral 4 is a second load circuit driven by the booster circuit 2. Reference numeral 5 denotes a voltage detection circuit for detecting a voltage drop when the main power supply 1 is momentarily stopped or when an instantaneous large current load is generated. The first voltage detection circuit 5 detects a voltage drop by the detection circuit 5. The boost circuit 2 is added to the load circuit 3.
A switching circuit 6 that supplies power more temporarily is provided.

The first load circuit 3 is a control means composed of a microcomputer or the like, has at least a memory (not shown), and has a power source input terminal 3a and resets when the power source voltage drops. The reset terminal 3b for inputting a signal is provided. In addition, the voltage detection circuit 5 detects a voltage drop when a shock or vibration is applied to the device for a short time to cause a momentary stop of the main power supply or an instantaneous large current load such as a motor start occurs. Therefore, upon detection of this voltage drop, the switching circuit 6 is switched and the power supply to the first load circuit 3 is switched from the main power supply 1 to the booster circuit 2 side.

Therefore, at the moment of chattering due to the contact of the battery or a large current load for starting the motor, power is supplied to the first load circuit 3 from the output of the booster circuit 2 and the first load circuit 3 operates without being reset. It is possible to continue. Further, the first load circuit 3 has a memory that is reset by a decrease in the power supply voltage due to consumption of the main power supply 1 or the like, and the voltage drop at that time is similar to the above-mentioned instantaneous voltage drop.
The reset signal is detected by the voltage detection circuit 5 and outputs a reset signal at the time of detection. A delay circuit 7 including a resistor R1 and a capacitor C1 is provided in a path between the output terminal 5a and the reset terminal 3b of the first load circuit 3. It is provided. The power is supplied from the booster circuit 2 via the switching circuit 6 for a certain time during which the delay circuit 7 is operating, and the voltage detection circuit 5 still detects a certain voltage or less after the elapse of the certain time. In this case, the reset signal is supplied to the first load circuit 3.

Next, a description will be given based on the specific circuit configuration diagram shown in FIG. In FIG. 2, transistors Q1 and Q
The voltage detecting circuit 5 is composed of the resistor 2, the resistor R2, the resistor R3, the resistor R4, and the diode D1. Transistors Q4 and Q7 are transistors that form the switching circuit 6 of FIG. 1, and include transistors Q3, Q5 and Q6 and resistors R6 and R6.
7, R8, R9, R10 are the transistors Q4, Q
7 and a transistor for controlling 7. The resistor R11 is a resistor for setting the output voltage of the booster circuit 2 to the rated operating voltage of the microcomputer of the first load circuit 3, and the diode D2 is a diode for preventing backflow. C4 is a capacitor for removing ripples generated inside the device, C3 is a power supply filter capacitor for the first load circuit 3, and C2 is a capacitor for removing ripples of the booster circuit. In addition, R1, R12, C1, Q8, Q9
Is a resistor, a transistor and a capacitor for glueing the first load circuit 3.

The operation of the power supply switching device configured as described above will be described below. First, in a normal operating state, a sufficient current flows through the resistor R3 to the resistor R3, the diode D1 side and the base of the transistor Q1, the transistor Q1 is in the ON state, and accordingly, the transistor Q2 is also turned on. _{Has a} battery voltage of −V _CESat , which is approximately equal to the battery voltage. Next, when the potential of the power supply line supplied from the battery decreases to a predetermined voltage due to the chattering of the power supply due to the shock or vibration of the device or the momentary large current load due to the motor start-up, the base potential of the transistor Q1 changes. Drop,
This transistor Q1 is turned off. Therefore, the transistor Q2 is also turned off, and when the voltage detection output transistor Q2 is turned off, the transistors Q3 and Q4 are turned off.
The FF is performed, and the power supply from the battery side is cut off. At the same time, the transistor Q5 is turned off, Q6 is turned on, and power is supplied from the output side of the booster circuit 2 to the first load circuit 3 through the resistor R11 and the diode D2. Further, even if the transistor Q2 is turned off, the transistor Q8 does not turn on unless the resistance R1 and the capacitor C1 are charged,
For the momentary stop, the first load circuit 3 can continue its operation without being reset.

[0014]

As described above, according to the present invention, when a momentary shock or vibration is applied to a device to cause a momentary stop of the main power source or an instantaneous large current load such as a motor start occurs, By detecting the voltage drop and switching the switching circuit, the power supply from the booster circuit can be supplied to the first load circuit, and the instantaneous stop due to chattering such as shock or vibration applied to the equipment can be controlled. It is possible to hold circuits, memories, etc.
The same can be done for sudden battery voltage fluctuations due to large current loads such as battery start-up, and in portable devices that are easily subject to shock and vibration, momentary power loss due to chattering of battery contact for a short time or motor start-up. It is possible to continue the operation of the device without holding the power source with a large-capacity capacitor against a sudden potential drop due to an instantaneous large current load such as.

Further, according to the present invention, when the voltage detection circuit detects a voltage drop, power is temporarily supplied from the booster circuit, and the first load circuit is reset after a certain delay time by the delay circuit. Therefore, when the voltage drops due to the exhaustion of the battery, a short-time shock or vibration is applied to the equipment to cause a momentary stop of the main power supply, or an instantaneous large current load such as motor start occurs, it is distinguished from the voltage drop. You will be able to do it.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a power supply switching device according to an embodiment of the present invention.

FIG. 2 is a specific circuit configuration diagram of the same.

[Explanation of symbols]

 1 Main Power Supply 2 Booster Circuit 3 First Load Circuit 4 Second Load Circuit 5 Voltage Detection Circuit 6 Switching Circuit 7 Delay Circuit

Claims (3)

[Claims] 1. A device having a main power supply supplied by using a battery as a power supply and a booster circuit for boosting and supplying the main power supply voltage, which is directly driven by the main power supply and operates by lowering the power supply voltage. A first load circuit in which a defect occurs, a second load circuit driven by the booster circuit, and a voltage drop when an instantaneous stop of the main power supply occurs or an instantaneous large current load occurs are detected. A voltage detection circuit and a switching circuit that temporarily supplies power to the first load circuit from the booster circuit when a voltage drop is detected by the detection circuit are provided. A power supply switching device configured to supply power from a booster circuit to a first load circuit when an instantaneous stop occurs or when an instantaneous large current load such as motor start occurs. 2. The power supply switching device according to claim 1, wherein the first load circuit is a control unit having a memory. 3. A device having a main power source supplied by using a battery as a power source and a booster circuit for boosting and supplying the main power source voltage, which is directly driven by the main power source and resets when the power source voltage drops. A first load circuit having at least a memory, a second load circuit driven by the booster circuit, a voltage detection circuit for detecting a voltage drop of the main power supply, and a first voltage detection circuit for detecting a voltage drop by the detection circuit. A switching circuit for temporarily supplying power to the first load circuit from the booster circuit; and a delay provided on a path for supplying a reset signal to the reset input terminal of the first load circuit upon detection of a voltage drop of the voltage detection circuit. And a first load after the delay time by the delay circuit, while temporarily supplying power from the booster circuit when a voltage drop is detected by the voltage detection circuit. A power supply switching device characterized by being configured to reset a circuit.