JPH05265599A - Power source supply device for microcomputer - Google Patents

Abstract

PURPOSE:To suppress useless power consumption in a microcomputer by cutting off power supply to the microcomputer when electronic equipment controlled by the microcomputer is not used for a long period. CONSTITUTION:The microcomputer 1 reads in the output signal of a switch detecting part 5 when a reset signal is inputted from a reset signal generating part 9, and energizes a semiconductor switching element 7 by controlling a conduction circuit 8 when confirming the open state of a switch 4. After that, the microcomputer monitors the output signal of the switch detecting part 5, and performs prescribed post-processing in a state where the power source is disconnected when confirming the closed state of the switch 4, then, cuts off the energized state of the semiconductor element 7 by controlling the conduction circuit 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for a microcomputer.

[0002]

2. Description of the Related Art Generally, an electronic device equipped with a microcomputer is designed such that the microcomputer constantly monitors the on / off state of a power switch with respect to a main power source, and when the on / off state of the power switch is confirmed, various electronic device components are initialized. After confirming that the power switch has been turned off by performing a predetermined start-up process such as erasing, post-processing such as writing and holding the contents of RAM (random access memory) to a non-volatile storage device is performed. It was

Therefore, in this type of electronic equipment, only the microcomputer is driven by a battery, or a circuit is constructed so that the main power is continuously supplied to the microcomputer even when the power switch is turned off. Even when the switch was turned off, the driving DC power was continuously supplied to the microcomputer.

[0004]

However, conventionally, since the microcomputer is still supplied with power even when the power switch of the main power supply is turned off, power is wasted when the electronic device is not used for a long period of time. It was great.

Therefore, the present invention is intended to provide a power supply device for a microcomputer, which has a simple structure without impairing the function of the microcomputer and which can prevent power consumption of the microcomputer.

[0006]

According to the present invention, there is provided a microcomputer power supply unit for supplying a driving DC power supply to a microcomputer and a self-restoring interposed in a power supply line connecting the power supply unit and the microcomputer. Type switch, a reset signal generator connected downstream of the switch and outputting a reset signal to the microcomputer when the voltage of the power supply line rises to a predetermined level, and a switch for detecting the closed state of the switch A detection unit, a semiconductor switching element connected in parallel to the switch on the power supply line, and an energizing circuit for energizing the semiconductor switching element are provided, and the microcomputer outputs the output of the switch detection unit when a reset signal is input. After reading the signal and confirming the closed state of the switch, energizing circuit Power-on control means for controlling the conduction of the semiconductor switching element and the output signal of the switch detection part while the semiconductor switching element is conducting by this means, and confirming the closed state of the switch, the power is turned off. And a power-off control unit that cuts off the conduction state of the semiconductor switching element by controlling the energizing circuit after performing the predetermined post-processing in 1.

[0007]

According to the present invention having such a configuration, when the switch is closed in the state where the direct current power is not supplied from the power supply unit to the microcomputer, the voltage of the power supply line is downstream from the switch. Since the voltage rises to the predetermined level, the reset signal generator outputs the reset signal to the microcomputer. Then, the microcomputer controls the energizing circuit to bring the semiconductor switching element into conduction. As a result, the switch is automatically opened because it is a self-reset type, but since the semiconductor switching element is in a conductive state, power supply to the microcomputer is continued.

When the switch is closed again in this state, the microcomputer carries out a predetermined post-processing when the power is cut off, and then the energizing circuit is controlled to cut off the conduction state of the semiconductor switching element. As a result, the power supply from the power supply unit to the microcomputer is stopped, and the waste of power is prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a microcomputer 1 constitutes a control unit main body of an electronic device. This microcomputer 1 is supplied from a battery 2 provided separately from the main power source of electronic equipment through a power supply line 3 and + 5V.
It is driven by the DC power supply.

The switch 4 provided with two normally open contacts 41 and 42 in parallel is a self-reset type switch.
1, 42 are interlocked. One normally open contact 41 is interposed in the power supply line 3 that connects the battery 2 and the microcomputer 1. The other normally open contact 42 is interposed in the line 6 connecting the battery 2 and the switch detection unit 5.

The switch detection section 5 detects the closed state of the switch 4, and is an NPN whose emitter is grounded.
Type transistor 51, a resistor 52 interposed in the line connecting the base of the transistor 51 and the other normally open contact 42, and a line connecting the collector of the transistor 51 and the power supply line 3 Resistance 5
2 and.

P-channel MOSFET (MOS-Filed Effect Transistor) which is a semiconductor switching element
Reference numeral 7 connects a base and a source to the upstream side of the switch 4 in the power supply line 3 and a drain to the downstream side of the switch 4 in the power supply line 3. That is, the MOSFET 7 is connected to the power supply line 3 in parallel with one normally open contact 41 of the switch 4.

In the MOSFET 7, the gate is connected to the collector of the NPN type transistor 81, and the source and the gate are connected via the resistor 71. The NPN transistor 81 has its emitter grounded.

The reset signal generator 9 monitors the voltage of the power supply line 3 and outputs a reset signal to the microcomputer 1 when the voltage rises to a predetermined level.

Reset terminal R of the microcomputer 1
Is connected to the reset signal generator 9, and the power supply terminal V is connected to the power supply line 3. The input port J of the microcomputer 1 is connected to the collector of the transistor 51 in the switch detector 5, and the output port Q is connected to the base of the transistor 81 via the resistor 82. Transistor 81 and resistor 82
Constitutes an energizing circuit 8 for energizing the MOSFET which is the semiconductor switching element.

The microcomputer 1 is programmed so as to execute the control shown in FIG. This control is started when a reset signal is input to the reset terminal R.

First, in ST1, the signal input to the input port J, that is, the output signal of the switch detector 5 is read. Then, when it is confirmed that this signal is at the low level "L", the switch 4 is closed. Therefore, at ST2, the signal level of the output port Q is set to the high level "H" to turn on the transistor 81 of the energizing circuit 8. , MOSFET7
To conduct. (Power-on control means) Next, if the input signal of the input port J is read in ST3 and it is confirmed that it is at the high level "H", the switch 4 is automatically restored to normal and opened. The processing after the set power-up is executed, and after the execution, the normal processing is started in ST5.

The microcomputer 1 constantly monitors the input signal of the input port J even while executing this normal processing. Then, if it is confirmed in ST6 that the input signal of the input port J has changed to the low level "L", the switch 4 is closed again. Therefore, in ST7, the preset processing after power-off is executed. .. When this post-processing is completed, the signal level of the output port Q is set to the low level "L" in ST8 to turn off the transistor 81 of the energizing circuit 8 and cut off the conduction state of the MOSFET 7. (Power Off Control Unit) In the present embodiment having such a configuration, when the switch 4 is closed in a state where the DC power from the battery 2 is not supplied to the microcomputer 1, the power supply line 3
A + 5V DC power source from the battery 2 is supplied to. This starts the microcomputer 1 and
A reset signal is sent from the reset signal generator 9 to the microcomputer 1. Then, the microcomputer 1 starts the control shown in FIG.

At this time, the transistor 51 of the switch detector 5 is on until the switch 4 is automatically restored,
The signal input to the input port J of the microcomputer 1 is at low level "L". Therefore, a high level “H” signal is output from the output port Q of the microcomputer 1.

Then, the transistor 8 of the energizing circuit 8
1 is turned on and the MOSFET 7 is turned on. Therefore, the switch 4 is automatically restored after a certain period of time and opened,
Since the MOSFET 7 is conducting, the + 5V DC power from the battery 2 is continuously supplied to the power supply line 3.
The microcomputer 1 performs normal processing after performing the processing after the power is turned on.

After that, when the switch 4 is closed again,
The signal input to the input terminal J of the microcomputer 1 changes from the high level "H" to the low level "L". As a result, the microcomputer 1 performs the process after the power is turned off. When the post-processing is completed, the signal output from the output port Q changes from the high level "H" to the low level "L".

Then, the transistor 8 of the energizing circuit 8
1 is turned off, and the conduction state of MOSFET 7 is cut off. Accordingly, the switch 4 is also automatically restored and opened, so that the power supply line 3 is not supplied with power from the battery 2. As a result, the microcomputer 1 stops its operation.

As described above, the apparatus according to the present embodiment has the battery 2 that supplies the driving DC power to the microcomputer 1.
A self-reset type switch 4 is provided on a power supply line 3 that connects the battery 2 and the microcomputer 1. Further, a reset signal generator 9 for outputting a reset signal to the microcomputer 1 when the voltage of the power supply line 3 rises to a predetermined level is provided on the downstream side of the switch 4, and the closed state of the switch 4 is detected. The switch detection unit 5 is provided. Further, a MOSFET 7 is connected in parallel with the switch 3 and an energizing circuit 8 for energizing the MOSFET 7 is provided.

When the reset signal is input, the microcomputer 1 reads the output signal of the switch detector 5 and, when the closed state of the switch 4 is confirmed, controls the energizing circuit 8 to make the MOSFET 7 conductive. In addition, the switch detector 5 with the MOSFET 7 turned on.
If the closed state of the switch 4 is confirmed by monitoring the output signal of the switch 4, after performing predetermined post-processing when the power is cut off, the energizing circuit 8 is controlled to program-control so as to cut off the conduction state of the MOSFET 7. ing.

Therefore, when starting to use the electronic device controlled by the microcomputer 1, the user presses the switch 4 separately from the power switch of the main power supply. Then, the microcomputer 1 and the battery 2
Is supplied and a reset signal is input from the reset signal generator 9 to start the microcomputer 1. Then, the MOSFET 7 becomes conductive and the power supply to the microcomputer 1 is continued. Therefore, the microcomputer 1 can perform normal processing such as monitoring the power switch of the main power supply.

On the other hand, when the electronic device is not used for a long time, the user presses the switch 4 separately from the power switch of the main power source. Then, the microcomputer 1
After the processing after the predetermined power-off in the
The conduction state of ET7 is cut off. As a result, the power supply to the microcomputer 1 is cut off, so that the power consumption of the battery 2 can be prevented and the life of the battery 2 can be extended.

In this case, a self-reset type switch 4 having two normally open contacts 41, 42 in parallel is used as a switch interposed in the power supply line 3, and a switching connected in parallel with this switch. MO as a means
SFET7 is used. Therefore, the switch detection unit 5 for detecting the closed state of the switch 4 can be composed of one transistor 51 and two resistors 52 and 53. Also,
The energizing circuit 8 includes one transistor 81 and one resistor 82.
Can be configured with. Therefore, the circuit configuration is simple and can be realized at low cost.

Although the battery 2 is shown as the power source for the microcomputer in the above embodiment, a + 5V DC power source generated by the main power source of electronic equipment may be used. Also in this case, since the power supply to the microcomputer 1 is cut off by the second operation of the switch 4, the power consumption of the main power supply can be reduced.

Further, in the above embodiment, two normally open contacts 4 are provided.
Although the self-recovery type switch 4 having 1, 42 in parallel is used, a self-recovery type switch having only one contact may be used. In this case, the switch detector 5
For this, it is conceivable to use a sensor (such as a limit switch or an optical sensor) that mechanically detects the operation of the switch 4.

In addition, various modifications can be made without departing from the scope of the invention.

[0032]

As described in detail above, according to the present invention, it is possible to provide a power supply device for a microcomputer, which has a simple structure and does not impair the function of the microcomputer, and which can prevent power consumption of the microcomputer.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing main control of the microcomputer in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Microcomputer, 2 ... Battery (microcomputer power supply part), 3 ... Power supply line, 4 ... Switch, 5 ... Switch detection part, 7 ... MOSFET (semiconductor switching element), 8 ... Energizing circuit, 9 ... Reset signal Generation part.

Claims (1)

[Claims] 1. A power supply unit for a microcomputer for supplying a driving DC power supply to the microcomputer, a self-reset type switch interposed in a power supply line connecting the power supply unit and the microcomputer, and this switch. A reset signal generator connected downstream of the power supply line and outputting a reset signal to the microcomputer when the voltage of the power supply line rises to a predetermined level; a switch detector that detects a closed state of the switch; A semiconductor switching element connected in parallel to the switch in a power supply line and an energizing circuit for energizing the semiconductor switching element are provided, and the microcomputer outputs the switch detection section when the reset signal is input. Do not read the signal and confirm the closed state of the switch. For example, power-on control means for controlling the energizing circuit to make the semiconductor switching element conductive, and monitoring the output signal of the switch detector in a state where the semiconductor switching element is made conductive by this means, and closing the switch. A microcomputer provided with a power-off control means for controlling the energizing circuit to shut off the conduction state of the semiconductor switching element after performing a predetermined post-processing when the power is turned off if the state is confirmed. Power supply device.