JPH09107641A - Power supply backup unit using dc-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To store a data memorized in a memory by outputting a predetermined operating voltage constantly to a memory IC until the voltage from a discharge circuit is reduced to a predetermined minimum data retaining voltage level. SOLUTION: A terminal of a battery B is grounded through a second resistor R2 and a transistor Q upon power interruption. First and second resistors R1, R2 divide n input applying voltage 5V and charges the battery B to sustain a voltage of 3.0V. A first diode D1 applies the voltage of battery B only to the DC-DC converter section 30 in power interruption. Data memorized in the memory is stored for a long time by feeding an output voltage of 5V to a microcomputer IC 13 until the voltage being fed from the battery B in power interruption in the backup mode, i.e., low power consumption mode, of DC-DC converter section 30 drops below the minimum data retaining voltage, i.e., 1.5V.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VTR power supply circuit, and more particularly, to a DC-DC (DC-DC) circuit capable of backing up a predetermined operating voltage during a power failure for a certain period of time to retain data stored in a memory in an IC. The present invention relates to a power supply backup device using a DC converter.

[0002]

2. Description of the Related Art Generally, when an input power supply is not applied during operation of a power supply unit of a VTR, that is, a power supply voltage applied during a power failure is linearly reduced to a constant voltage. VTR
Since a large number of ICs that remember data in a device have different characteristics, some ICs operate even when the voltage drops between 5V and 3V, while some ICs always operate only at a constant 5V voltage. Therefore, an IC that constantly operates at a voltage of 5V in this way is approximately 4.
The high (H) state of 5 to 5.0V must be maintained. The conventional technique as described above will be briefly described with reference to FIGS. 1 and 2.

FIG. 1 is a circuit diagram showing a conventional power backup device for supplying power to an IC. In FIG. 1, the input voltage is 5V, which is input to the power supply input terminal Vcc of the microcomputer IC13 through the second diode D2. Here, although the terminals of the microcomputer IC 13 are composed of a large number of terminals, only the parts necessary for explaining the conventional technique are shown. Also,
The 5V input voltage is transmitted to the reset IC 11 through the first diode D1. When a voltage lower than a predetermined operating voltage is applied to the reset IC 11, the reset IC 11 applies a signal to the reset terminal of the microcomputer IC 13 to reset the operation of the microcomputer IC 13. Further, the input voltage is transmitted to the ground through the third resistor R3 and is also supplied to the base terminal of the transistor Q. Transistor Q is a PNP transistor, the collector end of which is connected to ground. The input voltage is supplied to the positive terminal of the first diode D1, and the first diode D1
The output of 1 is supplied to the + terminal of the battery B and the input terminal of the reset IC 11. The negative terminal of the battery B is connected to the emitter terminal of the transistor Q. Battery B is 3.
It is possible to charge and discharge 0V capacity. Then, one end is connected to the emitter terminal of the transistor Q, the other end is connected to the input voltage and the positive terminal of the first diode D1, and one end is connected to the emitter terminal of the transistor Q and the negative terminal of the battery B. A second resistor R connected to the other end and grounded
Reference numeral 2 divides the applied input voltage of 5 V and charges the battery B while keeping 3.0 V (voltage difference between both ends). The voltage of the battery B at the time of power failure is the microcomputer IC of the first diode D1.
Only 13 is applied. The first capacitor C1 discharges the charged voltage to the backup terminal of the microcomputer IC13 to keep the operating voltage for a predetermined time. Here, the backup refers to supplying a predetermined voltage DC in order to retain the data memorized in the memory in the predetermined IC when the power of a device such as a VTR is turned off.

FIG. 2 is a conceptual diagram for explaining a voltage change state according to a power failure time in the circuit diagram of the power backup device of FIG. In the graph of FIG. 2, the horizontal axis represents time t and the vertical axis represents voltage v. The voltage that passes through the second diode D2 and is input to the power supply terminal Vcc of the IC sharply drops after the power failure point C as shown by the line a in FIG. The signal fed back through the backup terminal of the microcomputer IC13 is a voltage that drops as shown by the line b in FIG. 2, and at this time, the IC retains the stored data in the memory. Here, T represents the backup time during which the backup is maintained due to the IC load. Depending on the IC, it may operate at a voltage that linearly drops to a certain voltage, but an IC that only has a memory for data, etc., will operate even when there is a power outage.
The voltage of 5V to 5V must be maintained. At this time, power cannot be supplied to the IC by the conventional backup method.

[0005]

SUMMARY OF THE INVENTION Therefore, in order to solve the above-mentioned disadvantages, an object of the present invention is to transform a DC voltage applied so that a constant operating power can be supplied to a predetermined IC even during a power failure of a VTR. There is provided a power backup device capable of storing data memorized in a memory by using a DC-DC converter which is a device for performing the above.

[0006]

In order to achieve the above-mentioned object, a feature of the present invention is that in a power supply backup device that backs up a predetermined voltage to retain data stored in a memory IC, it receives an input voltage. A discharge circuit including a battery that can be charged and discharged to a predetermined voltage, and a voltage that is discharged from the discharge circuit as an input, and a constant operating voltage is always output to the memory IC until the input voltage is reduced to a predetermined minimum data holding voltage value. The power backup device includes a DC-DC converter unit.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 is a circuit diagram showing a power supply device according to a preferred embodiment of the present invention. FIG. 3 includes the configuration of FIG.
A DC converter unit 30 is added and configured. Here, since the reset IC shown in FIG. 1 operates according to a general conventional technique, its description is omitted. Components in FIG. 3 that perform the same functions as those in FIG. 1 are numbered the same.

In FIG. 3, the positive terminal of the battery B is D
It is connected to the C-DC converter unit 30. The terminals of the DC-DC converter unit 30 will be briefly described. The number terminal of the DC-DC converter unit 30 is Vin (input terminal), the number terminal is ON / OFF, the number terminals are SEL1 and 2, the number terminals are Vout (output terminal), and the number terminals are Vsw and the third capacitor. It is output to C3 and is grounded. The number terminal is connected to the coil L and is grounded through the fourth capacitor C4. The number terminal is connected to the ground. Input voltage is 5
V and passes through the second diode D2, and the microcomputer IC
13 is input to the power input terminal Vcc. Input voltage is third
It is transmitted to the ground through the resistor R3 and is also supplied to the base terminal of the transistor Q. The positive terminal of the battery B is connected to the output terminal of the first diode D1, the negative terminal of the battery B is connected to the emitter terminal of the transistor Q, and the positive terminal of the battery B is connected to the DC-DC converter unit 30. If the negative terminal of the battery B is directly grounded at the time of power failure, the life of the battery B is shortened.
And through transistor Q to ground. As shown in FIG. 1, the first resistor R1 and the second resistor R2 divide the applied input voltage of 5V to charge the battery B while maintaining 3.0V (voltage difference between both ends). The first diode D1 converts the voltage of the battery B during a power failure into the DC-DC converter unit 3
Only applied to 0. DC-DC converter unit 30
In the low power consumption mode, which is the backup mode, the 5V output voltage is supplied to the microcomputer IC13 until the voltage supplied from the battery B at the time of power failure becomes less than the minimum data maintaining voltage of 1.5V, and is stored in the memory for a long time. Keep the data that you have.

FIG. 4A is a conceptual diagram for explaining a voltage state in which a constant voltage is supplied to a predetermined IC during a power failure in the power supply device of FIG. Fig. 4 (A) shows DC-D during power failure
FIG. 5 is a conceptual diagram showing a reduced voltage input to a power supply input terminal Vin of the C converter unit 30.
FIG. 7 is a conceptual diagram for explaining a voltage falling from V to 1.5V which is a memory data minimum sustain voltage value. FIG.
FIG. 4B shows an embodiment of the present invention in which the DC-DC converter unit 30 is added, and the voltage passing through the DC-DC converter unit 30 is not a voltage-decreasing mode as shown in FIG. 1.5V which is the minimum sustaining voltage value of data
It is a conceptual diagram for explaining the apparatus of the present invention that constantly supplies 5 V to the microcomputer IC 13 until it becomes. Where T
Indicates a backup maintenance time, and C indicates a power failure point.

[0010]

As described above, the present invention provides a DC-DC converter for a VTR power supply circuit, which is capable of always backing up a predetermined operating voltage in the event of a power failure to retain the data memorized in the memory in the IC. The power backup device used is provided to enable continuous use of the VCR's remembered data.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a conventional power backup device.

FIG. 2 is a conceptual diagram for explaining a voltage change state according to a power failure time in the circuit diagram of the power backup device of FIG.

FIG. 3 is a circuit diagram illustrating a power backup device according to a preferred embodiment of the present invention.

4A and 4B are conceptual diagrams for explaining a voltage state in which a constant voltage is supplied to a predetermined IC during a power failure in the power backup device of the present invention.

[Explanation of symbols]

 13 Microcomputer IC 30 DC-DC converter part R1, R2, R3 resistance D1, D2 diode C2, C3, C4, C5 capacitor B battery L coil

Claims (2)

[Claims] 1. A power supply backup device capable of supplying a predetermined voltage to retain data stored in a memory IC, the discharge circuit including a battery capable of receiving and charging an input voltage to a predetermined voltage, and the discharge circuit. A power supply backup device including a DC-DC converter unit that receives a discharged voltage as an input and always outputs a constant operating voltage to the memory IC until the input voltage is reduced to a predetermined minimum data holding voltage value. 2. The power supply including a DC-DC converter according to claim 1, wherein the time when the output voltage of the DC-DC converter is supplied to the memory IC can be changed by the load of the memory IC. Backup device.