JPS6041795Y2 - power supply - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a power supply device, for example, a power supply device that protects data in a CMOS-RAM.

In recent years, many memory boards have been used that back up the C-MO5 RAM with a battery and protect the data in the RAM when the power is turned off.

In a device that is powered for a very short time in a day, the time to charge the backup battery is short, so the battery gradually discharges, making it impossible to protect the data in the RAM.

The purpose of this invention is to prevent the battery from discharging and protect the data in the RAM even if the device is energized for a very short time each day.

In order to achieve this objective, in this invention, a small-capacity auxiliary power supply device that charges a backup battery when the main power supply device is cut off is provided in a separate system from the main power supply device.

Further, a transistor switch is provided between the secondary power supply device and the battery, and the transistor switch is controlled by a timer to periodically charge the battery.

According to this invention, since the capacity of the secondary power supply device of a separate system is small, power consumption can be reduced and the initial objective can be distantly achieved.

Furthermore, since the above-mentioned transistor switch is controlled by a timer, overcharging can be prevented.

This invention will be explained in detail below with reference to the illustrated embodiments.

In Figure 1, there is 1 RAM (Random Access Memory).
It is shown as.

This RAM 1 receives power from the main power supply device 2 .

The main power supply device 2 is composed of a rectifier circuit and a DC stabilizing circuit.

Commercial power is applied to terminals 3 and 4. The primary side of a transformer 6 for the main power supply 2 is connected to these terminals 3 and 4 via a switch 5.

Switch 5 is closed when operating control device 19, ie between times t1 and t5 shown in FIG.

During this time, the input side of the main power supply device 2 is connected to the commercial power supply via the transformer 6.

After a while after the switch 5 is closed, the output voltage of the main power supply 2 reaches a constant voltage (time t4 in FIG. 2).
.

In order to detect that the output voltage of this main power supply device 2 has reached a predetermined voltage slightly lower than the constant voltage, a power supply detection circuit 7
A transistor switch 8, which is opened and closed by the output of the voltage detection circuit 7, is connected between the main power supply device 2 and the power supply terminal of the RAM 1.

The output side of the transistor switch 8 is further connected to the positive terminal of a battery 10 via a resistor 9.

The transistor switch 8 is turned on from time t3 before time t4 to time t6 after time t5.

While this is on, DC voltage is supplied from the main power supply device 2 to the RAM 1 and the control device 19, and the battery 10 is charged.

After the operation of the control device is stopped and switch 5 is opened, the output voltage of main power supply device 2 is turned off, transistor switch 8 is opened, and DC voltage is supplied from battery 10 to RAM 1 via diode 11.

A secondary power supply is shown as 12.

This input side is connected to terminals 3 and 4 via a transformer 13.

Similarly to 2, the sub power supply device 12 is composed of a rectifier circuit and a DC stabilizing circuit.

The secondary power supply device 12 and the transformer 13 are connected to the battery 10.
Main power supply unit 2
, is extremely small compared to the capacity of the transformer 16.

The output side of the slave power supply device 12 is connected to a transistor switch 14.
, battery 10 via resistor 15 and diode 16
Connected to the positive pole of.

A voltage detection circuit 17 is provided to detect that the output voltage of the main power supply device 2 has decreased.

The output signal of this voltage detection circuit 17 is at the time t shown in FIG.
It is on from 2 to t7.

The timer 18 is controlled by the output signal of the voltage detection circuit 17, and periodically outputs T1 while the output signal is on.
It produces an output signal that is on for T2 and off for T2.

This output signal opens and closes the transistor switch 14.

As a result, as shown in FIG.
Charging is stopped for a certain period of time T1, and then the battery 1o is charged again for a certain period of time T1.

Although not shown, the voltage detection circuit 17.timer circuit 18. Power is supplied to the power terminal of the transistor switch 14 from the output terminal of the slave power supply device 12 .

As mentioned above, according to this invention, the DC load such as the control device 19 and the RAM that are operated only for a predetermined time in a day
1, the main power supply 2 for a predetermined period of time to supply power.
Even if the battery 1 is operated, the battery 1 can be appropriately charged by a small-capacity secondary power supply device provided in a separate system.

[Brief explanation of the drawing]

FIG. 1 is an electrical block diagram showing an embodiment of this invention, and FIG. 2 is a time chart showing its operation. 2... Main power supply device, 5... Switch,
1o...Song battery, 12...Sub power supply device, 1
4. Song transistor switch, 18. Song timer.

Claims (1)

[Scope of Utility Model Registration Claim] A main power supply device that supplies power to a DC load that is operated only for a predetermined period of time during the day, and whose input side is connected to an AC power source to generate a constant DC voltage, and a small-capacity main power supply device. a secondary power supply device, a switch for opening the input side of the main power supply device other than the predetermined time, a backup battery that supplies power to the memory when the AC power supply is cut off, and an output of the main power supply device. A timer circuit that turns on an output signal at regular intervals when the voltage falls below a predetermined value, and a transistor switch operated by the output signal of the timer circuit are provided, and while the main power supply device is generating a constant DC voltage, A power supply device configured to supply power to the DC load and charge the backup battery, and to charge the backup battery from the slave power supply device when the transistor switch is turned on.