JPS6280714A - Power supply switching circuit - Google Patents

Abstract

PURPOSE:To minimize an adder and to attain precise switching operation with an inexpensive non-lock switch by providing a microprocessor with a power supply switching control function. CONSTITUTION:When a non-lock type switch 5 is depressed, a transistor (TR)4 is connected and electric power is supplied from a power source E to the microprocessor 7 and a load 8. In accordance with power supply, the microprocessor 7 turns a control output line Lc to a high level H to connect a TR6. Even if the switch 5 is released under said state, the TR4 is continuously connected because the TR6 is connected. When the switch 5 is depressed to disconnect the power supply, the microprocessor 7 detects that a power feed input signal monitoring line LM has been earthed through a diode 9 and turned to a low level L and turns the control output line Lc to the low level L. Thereby, the TR6 is disconnected, and even if the switch 5 is released, the TR4 is not connected and power fed to the load 8 is interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a power switch circuit suitable for battery-powered electronic devices such as portable radio telephones.

[Background of the invention]

2. Description of the Related Art Power switch circuits that use lock-type switches have conventionally been used as power switch circuits in battery-powered electronic devices such as portable radio telephones.

FIG. 6 shows a power switch circuit for an electronic device according to the above-mentioned prior art, in which 1 is a lock type switch.

2 is a PNP) transistor, 3 is a load, and E is a power supply.

In the figure, when switch 1 is closed, the base of transistor 2 is grounded, transistor 2 is turned on, and power is supplied from power source E to load 3. When switch 1 is opened, transistor 2 is turned off and the load is 3 is stopped.

In such a power switch circuit, a lock type switch is used as the switch 1, which has the disadvantage of being expensive.

In addition, the power switch circuit using Taranas・rtsuchi,
For example, it is shown in the Tyl child outlook special volume, Electronics circuit idea collection, 79 (page 69), published by Seibundo Shinkosha Co., Ltd. on May 25, 1972.

The above conventional power switch circuit using a touch switch uses a CMO8F'ET element as the touch switch, and therefore has disadvantages in that the resistor is expensive and the operation is unstable.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a power switch circuit that uses a non-lock switch with an hour wheel mechanism and can perform reliable switch operation by touch operation.

[Summary of the invention]

In order to achieve this object, the present invention eliminates electronic equipment having a microprocessor as a control circuit, and provides a power switch control function as a function of the microprocessor, thereby minimizing additional circuitry and reducing the cost. It is unique in that it uses a non-locking switch to ensure reliable switch operation.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 6 is an NPN transistor (second transistor), 7 is a microprocessor, 8 is a load, 9 is a diode, and E is a power supply. The microprocessor 7 mainly functions as a control circuit for the electronic device, and in the present invention, a power switch control function is added thereto.

In the figure, a non-locking switch 5 is manually operated, and when it is pressed, a transistor 4 becomes conductive, and power is supplied from a power source E to a microprocessor 7 and a load 8.

In response, the microprocessor 7Fi sets the control output line Lc to a high level I, making the transistor 6 conductive. In this state, even if the switch 5 is released, the transistor 4 continues to be conductive because the transistor 6 is conductive.

Thereafter, the microprocessor 7 monitors the state of the power switch circuit by monitoring the power supply input signal monitoring line Lu. When the power supply input signal monitoring line LM is at a high level (H), it is determined that the switch 5 is not grounded, that is, the switch 5 is not pressed, and the control output line LC is maintained at a high level (H), and the load 8 to continue power supply.

Next, when stopping the power supply to the load 8, that is, turning off the power, when the switch 5 is pressed, the microprocessor 7 causes the power supply input signal monitoring line LM to be grounded via the diode 9 and set to low level (L). This is detected and the control output line LC is set to low level (L). Therefore, transistor 6 becomes non-conductive, and even if switch 5 is released, transistor 4 does not become conductive, and power is not supplied to the load.

In this way, the power can be turned off by touching the non-locking switch 5.

FIG. 2 is a flowchart for executing the power switch control function of the microprocessor in FIG.

In the third country, the macro processor has switch 5 (
When the button (Fig. 1) is pressed (power supply turned on), the power supply flag is reset and the control output line is set to high level. Next, since the power supply input monitoring line No. 100 is at a high level (H), a power supply flag is set, and power is supplied. When turning off the power, the power supply input signal monitoring line becomes low level (L) due to the switch 'f-5 being pressed, and the power supply flag is set.
The power is turned off) and the control output line is set to low level (L).
The power supply is stopped and the control program is terminated.

〔Effect of the invention〕

As explained above, according to the present invention, reliable power supply operation can be performed by adding a simple front path to an electronic device having a microprocessor, and the present invention is superior in that it eliminates the disadvantages of the prior art described above. A functional power switch circuit can be provided.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a power switch circuit according to the present invention, FIG. 2 is a flowchart for executing the power switch control function of the microprocessor in FIG. 1, and FIG. 3 is a circuit diagram showing a power switch circuit according to the prior art. FIG. 2 is a circuit diagram for explanation.

Claims (1)

[Claims] a power source, a load supplied with power from the power source, a microprocessor, a first transistor interposed between the power source and the load, and a control output of the microprocessor to conduct the first transistor. In the power switch circuit for an electronic device, the microprocessor mainly controls the electronic device and monitors the power supply input. It has a power switch control function for controlling the second transistor, and supplies power to the load by operating the non-locking switch to make the first transistor conductive, and also makes the second transistor conductive. A power switch circuit characterized in that this state is maintained and the second transistor is rendered non-conductive to stop power supply to the load by the next operation of the non-lock type switch.