JPH02246738A - Power unit - Google Patents

Abstract

PURPOSE:To extend a backup period by giving instructions from a microcomputer after turning OFF an external voltage supply according to the voltage state of a backup power source and by charging a backup secondary battery through a timer means time-set beforehand. CONSTITUTION:Only when the source voltage of a microcomputer 1 rises from the reset voltage and less of a memory 1C by the detecting means 1B for detecting a voltage at the time of rising of the source voltage of the microcomputer 1, a backup secondary battery 2 is charged with electricity even in the backup mode by a timer means 1D time-set beforehand. Therefore, the voltage of the backup secondary battery 2 is sufficiently high even if the time for applying external power by an ordinary control switch 4 is short. Thus, it is possible to extend a backup period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a power supply device in an apparatus using a microcomputer, and particularly to a power supply device using a backup power source.

Conventional technology In recent years, devices using microcomputers have been developed.

The number of computers has rapidly increased, and microcomputers have come to be installed in various types of equipment.

An example of a power supply circuit for a microcomputer equipped with a conventional backup power supply will be described below with reference to the drawings.

FIG. 6 shows a power supply circuit for a microcomputer equipped with a conventional backup power supply.

1' microcomputer, 1' control means and 1'
Equipped with 7C- memory. 2 is for backup 2
In the secondary battery, 4 is an operation switch, 5, 6.7 are transistors, and 3, 9, 10.11 are resistors.

The operation of the microcomputer power supply circuit equipped with the backup power supply configured as described above will be described below.

The memory 1'G of the microcomputer 1' is
The backup secondary battery 2 can be maintained even without an external power source. In normal use, by turning on the operation switch 4 once, the transistor 6 is turned on, the transistor 7 is turned on, and the transistor 6 is turned on, and power is supplied from the outside to the microcomputer 1', and the transistor 6 is turned on. When the ON signal is input to the preset control means 17, a holding output is output, the transistor 7 is kept on, and the external power is continuously supplied. On the other hand, when it is off, the operation switch 4 is turned on again and the on signal of the transistor 6 is inputted to the control means 1'.

The signal for holding the transistor 7 from the control means 1' is removed, the transistor 6 is turned off, and the supply from the external power source is stopped.

Problems to be Solved by the Invention However, with the above configuration, if the external power is not supplied for a long time during backup, the voltage supplied to the microcomputer will gradually decrease, and eventually the memory will turn off. The problem was that the voltage reached the point where the memory was erased. Furthermore, in order to extend the backup time, the backup secondary battery must be made larger, which poses a problem in that the device cannot be miniaturized.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a power supply device for a microcomputer that is equipped with a backup power source that can extend the time required to reach the memory off voltage during backup, and can reduce the size of the device.

Means for Solving the Problems In order to solve the above problems, the power supply device of the present invention includes a detection means for detecting the power supply voltage in the microcomputer, and detects the power supply voltage after the external voltage supply is turned off according to the voltage state of the backup power supply. This device is configured to issue an instruction from a microcomputer control means, issue an output signal from a timer means with a preset time, and charge a backup secondary battery from an external power source for a preset time.

Effect of the present invention With the above-described configuration, when the voltage level of the backup power source is lower than the memory reset voltage of the microcomputer, the microcomputer is supplied with the external power source, and after the supply is stopped, the backup power source 2 is supplied for the timer setting time. By controlling the next battery to be charged from an external power source, the time required to supply the external power to the microcomputer using a switch that normally operates the microcomputer can be shortened, and it can also be used as a backup when the external power supply stops. Even when the voltage of the secondary battery is low, the backup secondary battery is charged for a preset time, and the output voltage is sufficiently increased after charging is stopped, thereby eliminating memory loss. Furthermore, since the backup secondary battery can be made smaller, the device can be made smaller.

Embodiment Hereinafter, a power supply device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a power supply device according to a first embodiment of the present invention, FIG. 2 is a control flowchart thereof, FIG. 3 is a timing chart for its operation switches, and FIG. 4 is a diagram showing a second embodiment of the present invention. FIG. 2 is a block diagram of an example power supply device.

In FIG. 1, 1 is a microcomputer, 1B is a detection means for detecting the microcomputer power supply voltage, and 1D is a detection means for detecting the microcomputer power supply voltage.
is a timer means, and 8 is a transistor that is turned on and off by the timer means 1D.

As explained in the conventional example, once the operation switch 4 is turned on, the transistor 7 is turned on in response to a power hold instruction from the control means 1 of the microcomputer 1, and external power is supplied by the transistor 6. Then, when the operation switch 4 is turned on again, the transistor 7 is turned off, and the transistor 6 is also turned off, and the microcomputer enters the backup mode, and voltage is supplied from the backup secondary battery. However, when the operation switch is turned on for the first time, the power supply voltage of the microcomputer 1 in the backup mode is
-10 reset voltage or less.

As shown in the flowchart in Figure 1@2, after the operation switch 4 is turned on for the second time, a timer operation command is entered, and as shown in Figure 3, even though the transistor 7 is turned off, the timer transistor 8 is turned on. However, the transistor 6 is turned on and charging of the backup secondary battery 2 from the external power source continues for a preset timer period, and the voltage of the backup secondary battery becomes sufficiently high after the timer is turned off.

As described above, according to this embodiment, the detection means that detects the rising voltage of the microcomputer's power supply enters the backup mode only when the microcomputer's power supply voltage rises below the memory reset voltage. However, by providing a circuit that charges the backup secondary battery using a preset timer means.

The voltage of the backup secondary battery will be sufficiently high even if the external power supply time using the normal operation switch is short.
The backup time can be extended, and the memory can be prevented from being reset more easily than in the past. (9) If the backup time is the same as in the past, the backup secondary battery can be made smaller, and the device can be made more compact.

FIG. 4 shows a case where the operating voltage of the microcomputer 1 is higher than the voltage Vaa of the external power supply. The DC-DC converter 19 converts the voltage of the external power supply into the microcomputer 1.
The input signal of the operation switch 4 shown in FIG.
4.15 to transistors 6 and 7,
The operation itself is similar to the first embodiment. .

As in the second embodiment, when the voltages are different, the power source for backup is often a primary battery, and in this case, a weighted structure is required to make it replaceable. In other words, a Do-DC converter is placed between the external power supply transistor and the microcomputer's power supply terminal, a secondary battery is used as the microcomputer's buffer lag power supply, and other detection, control, and timer methods are used. By making it the same as the first embodiment, the effect of miniaturization is greater than that of the first embodiment, and by operating the timer only when the voltage rises from below the reset voltage,
Power consumption of external power supply can be minimized.

Effects of the Invention As described above, the present invention includes a backup power source, a detection means for detecting the voltage level of the power source at a preset level, an input signal for supplying power from an external power source, and a By providing a power supply device configured to supply external power to the microcomputer and to supply and charge the backup secondary battery using control means and timer means corresponding to the signal, the memory of the microcomputer can be used to protect the memory of the microcomputer from a drop in backup voltage. This makes it possible to extremely reduce the opportunity and time for the power supply to disappear, and to downsize the power supply device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a power supply device according to a first embodiment of the present invention, FIG. 2 is a control flowchart thereof, FIG. 3 is a timing chart for its operation switches, and FIG. 4 is a diagram of a second embodiment of the present invention. Block diagram of the power supply in
FIG. 6 is a block diagram of a conventional power supply device. 1M: Control means, 1B: Detection means, 1G: Memory, 1D: Timer means, 2: Backup secondary battery , 3.9-1
2...Resistance, 4...Operation switch, 6-8
...Transistor. Name of agent: Shigetaka Awano for patent purposes! ,
9.10.11.12--b anti-4- cold sweat switch 6.6.1. l3-)-Lancista (1 layer-) C2mm)! −−− Microcomputer

Claims (2)

[Claims] (1) A backup secondary battery power supply for the microcomputer, a power supply circuit means for supplying power supply voltage from an external power supply to the microcomputer and the secondary battery power supply, and a voltage level of the secondary battery power supply set in advance. It is characterized by comprising a detection means for detecting at a set level, and a timer means for enabling the power supply circuit means to supply power for a certain period of time when the voltage detected by the detection means falls below the set level. power supply. (2) The power supply device according to claim 1, wherein the power supply circuit means includes a first power supply circuit based on a manually operated switch, and a first power supply circuit controlled by a control means of a microcomputer and controlled by a timer means. 2. A power supply device comprising: 2 power supply circuits.