JP2000060128A - Memory backup circuit for electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption at backup, in an electronic apparatus which is equipped with a memory to store each kind of setting information inside the apparatus, and is so constituted as to back this up at all times. SOLUTION: For this memory backup circuit, a power switch 2 is on the side of b at off (at backup) of the power of an apparatus, and a weak voltage is generated on the secondary side of a power transformer 1 by applying a current to the power transformer 1 through a small capacity (for example, 0.2 μF-0.5 μF) of a capacitor 8, and sufficient voltage for a microcomputer 7 to stop the normal action and perform only the memory retention, of though it is completely insufficient to operate the apparatus, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for supplying power for backing up a memory of an electronic device.

[0002]

2. Description of the Related Art In recent years, many electronic devices are provided with a microcomputer circuit, and the microcomputer circuit controls the functional operation of the device. In these devices, for example, a memory built in the IC of the microcomputer circuit, a memory IC external to the microcomputer circuit, a gate array, etc.
Store the settings of various states required during operation of the device,
The next time the device is used, it is not necessary to set the operating conditions and the like of the device from the beginning, and many are designed so that they can be used immediately under the same conditions as the previous time.

As information to be stored, for example, in audio equipment and the like, various servo characteristic information of a disk reproducing device, preset channel information for a tuner circuit,
It covers a wide variety of surround information for amplifier circuits and setting information for equalizers.

FIG. 2 shows a conventional device, in which 11 is a power transformer, 12 is a power switch, 1
3 is a rectifying / smoothing circuit, 14 is a voltage stabilizing circuit, and 17 is a microcomputer circuit. Reference numeral 15 denotes a backflow prevention diode 1 provided between the voltage stabilizing circuit and the microcomputer circuit 17.
Reference numerals 5 and 16 denote backup capacitors.

When the apparatus is operating, the power switch 12 is closed, and the power transformer 11 is connected to a commercial AC power source. Power is supplied to the microcomputer circuit 17 through the backflow prevention diode 15, and at the same time, the backup capacitor 16 connected in parallel to the power supply terminal of the microcomputer circuit 17 is charged for backup.

The line connected in parallel with the backflow prevention diode 15 to the microcomputer circuit 17 without passing through the backflow prevention diode 15 is that the microcomputer circuit 17 monitors the power supply voltage and supplies the necessary voltage. This is for determining whether the normal operation is performed and the power supply switch is turned off or the necessary voltage is not supplied due to a power failure or the like, the normal operation is stopped, and the backup operation for retaining the memory is performed. . When the device is not operating, the microcomputer circuit 17 stops the operation of the clock, and performs only the holding operation of the built-in memory circuit (not shown). In addition, the voltage required at this time may be a considerably lower voltage than when the microcomputer circuit 17 is normally operating, and the required power is extremely small.

[0007]

As described above, in the above-described circuit, the memory backup is performed by using the electricity charged in the backup capacitor 16. However, the capacity of the capacitor may not be sufficient to provide the desired time (period) for backup. Therefore, it is conceivable to use dry batteries or rechargeable batteries in place of capacitors. There is a problem that the battery is likely to be deteriorated during use for a long period of time and an accident that the electrolyte leaks out easily occurs.

In FIG. 2, a power switch 12 is not provided on the primary side of the power transformer, and a power switch is provided on a line going to a subsequent circuit via a voltage stabilizing circuit 14 so as to turn on / off the power of the equipment. It is also conceivable that the power can be turned off and the microcomputer circuit 17 is always supplied with power. With this configuration, the contents of the memory are retained as long as it is connected to the commercial AC power supply, but the power transformer has a loss, and even if there is no load, the power transformer itself consumes power. I will. Such wasteful energy consumption is a very serious problem from the viewpoint of global environmental protection, which has recently become a global problem.

[0009]

In order to solve the above-mentioned problems, the present invention provides a transformer, switch means provided between a primary winding of the transformer and a commercial AC power supply, A rectifying / smoothing circuit connected to the secondary winding,
No memory backup circuit is provided for an electronic device including a microcomputer circuit which is supplied with power from the rectifying / smoothing circuit and controls the operation of the device, and a capacitor provided between the switch means and a primary winding of a transformer. It is assumed that.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an electronic apparatus to which a memory backup circuit according to the present invention is applied. In FIG. 1, 1 is a power transformer, 2 is a power switch,
3 is a rectifying / smoothing circuit, 4 is a voltage stabilizing circuit, and 7 is a microcomputer circuit. Reference numeral 5 denotes a backflow preventing diode provided between the voltage stabilizing circuit 4 and the microcomputer circuit 7,
Normally, power is supplied to the microcomputer circuit 7 via the diode 5. Reference numeral 6 denotes a backup capacitor, and reference numeral 8 denotes a small capacitor (for example, 0.2 μF to 0.5 μF) provided in parallel with the line going to the power transformer via the power switch.
Of the capacitor.

Normally, when the device is operating, the power switch 2 is on the side A, and the primary side of the power transformer 1 is connected to the commercial AC power supply via the power switch 2. The secondary side of the power transformer 1 is DC-converted by a rectifier / smoothing circuit 3, adjusted by a voltage stabilizing circuit 4, and further supplied to a microcomputer circuit 7 through a backflow preventing diode 5.

In order to turn off the power of the device, the power switch 2 is switched to the side B. Here, when the power transformer 1 is energized through the small-capacity capacitor 8, a weak voltage is generated on the secondary side of the power transformer 1, which is not enough to operate the equipment.
However, the voltage becomes sufficient to stop the normal operation and perform only the memory retention.

In this state, the power transformer 1
Since the current flowing to the next side is much smaller than in the normal operation, the power consumption in the standby state can be significantly reduced.

[0014]

As described in detail above, according to the present invention, a transformer, switch means provided between a primary winding of the transformer and a commercial AC power supply, and a secondary side of the transformer A rectifying / smoothing circuit connected to the winding, a microcomputer circuit supplied with power from the rectifying / smoothing circuit to control the operation of the device, and a capacitor provided between the switch means and the primary winding of the transformer. Therefore, as long as the device is connected to a commercial AC power supply, there is no need to worry about loss of memory, and there is an effect that extremely low power consumption is required even during a memory backup operation.

[Brief description of the drawings]

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

FIG. 2 is a circuit block diagram showing a conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power transformer 2 Power switch 3 Rectifier / smoothing circuit 4 Voltage stabilization circuit 5 Backflow prevention diode 6 Backup capacitor 7 Microcomputer circuit 8 Capacitor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B011 DB01 DB11 EA08 JA04 5G015 FA08 FA16 GB01 HA15 JA05 JA62 KA03 5H006 AA05 CA08 CB01 CC01

Claims (1)

[Claims] 1. A transformer, switching means provided between a primary winding of the transformer and a commercial AC power supply, and a rectifying / smoothing circuit connected to a secondary winding of the transformer.
A memory for an electronic device, comprising: a microcomputer circuit which is supplied with power from the rectifying / smoothing circuit and controls the operation of the device; and a capacitor provided between the switch means and a primary winding of a transformer. Backup circuit.