JPH0562157U - Battery backup circuit - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a device that can confirm the backup status in the event of a power failure. [Structure] The backup power is supplied to the load circuit when the AC power supply is interrupted, and the battery BAT that is charged from the AC power supply when energized and the output voltage of the battery are input, and the minimum required to back up the load circuit is input. Comparator CMP for comparing whether there is a voltage or more, element RM for storing the output signal of the comparator, switching means RL for switching and connecting the battery to the comparator and the AC power source side, and energization of the AC power source At this time, there is provided switching control means for connecting the battery to the comparator by the switching means and then connecting the battery to the AC power source side.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a battery backup circuit.

[0002]

[Prior Art]

 FIG. 3 is a configuration block diagram of a conventional device. In the figure, an AC adapter is connected to a commercial AC power source and outputs a DC current. The DC-DC converter receives the DC power sent from this AC adapter and supplies a stabilized DC voltage to the load circuit. The battery supplies electric power in place of the AC power supply in the event of a power failure, and trickle charges from the AC power supply when energized. The load circuit receives power from the battery when there is a power failure, so it does not hinder operation even if there is a momentary power failure.

[0003]

[Problems to be solved by the device]

 However, since there is a limit to the capacity of the battery, the capacity of the battery may be exhausted during backup and the load circuit may not be normally backed up. Therefore, it is necessary to confirm the backup state of the load circuit when the commercial power is turned on, but when the power is turned on, charging is started and the battery voltage is not measured. was there. It is also possible to monitor the battery voltage during backup, but even if the battery capacity was detected, it was necessary to retain that information separately.

The present invention solves such a problem, and an object of the present invention is to provide an apparatus capable of confirming a backup state at the time of power failure.

[0005]

[Means for Solving the Problems]

 The present invention, which achieves such an object, supplies a backup power to the load circuit during a power failure of the AC power supply, and inputs a battery BAT that is charged by the AC power supply when the power is on and the output voltage of the battery. Then, a comparator CMP for comparing whether or not there is a minimum voltage necessary for backing up the load circuit, an element RM for storing the output signal of this comparator, and the battery are connected by switching between the comparator and the AC power supply side. And switching control means for connecting the battery to the comparator by the switching means at the start of energization of the AC power supply, and thereafter connecting the battery to the AC power supply side.

[0006]

[Action]

 The switching means and the switching control means carry out a sequence of checking the voltage of the battery at the start of energization. The comparator inspects the voltage for backup in case of power failure, and the inspection result is stored in the memory element. On the load circuit side, you can access this storage element and check the backup.

[0007]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention. It is to be noted that the description of the components in FIG. 1 having the same functions as those in FIG. In the figure, the battery BAT supplies back-up power to the load circuit when the AC power supply is interrupted and is charged by the AC power supply when the AC power is supplied, and a secondary battery such as a NiCd battery is used. The comparator CMP checks the output voltage of the battery when the power is restored, and compares it with the minimum voltage required to back up the load circuit. The resistor Rf has substantially the same impedance as that of the load circuit and generates a battery voltage corresponding to the load current sent from the battery to the load circuit. The voltage generated by the resistor Rf is sent to one terminal of the comparator, and the reference voltage source Vref is connected to the other terminal. The reference voltage Vref is a voltage corresponding to the back-up voltage of the load circuit. The storage element RM is a general memory circuit and stores the output signal of this comparator. The alarm unit is a memory element that outputs an alarm when the backup voltage is too low, and includes a light emitting diode LED connected to the power supply line Vcc and a register REG accessible from the load circuit side.

The switching control means is composed of a voltage monitoring circuit V _IN and a pulse generation circuit MMB. When the power is restored, the battery backup voltage test using a comparator is performed to start the charging operation. The voltage monitoring circuit V _IN detects the power recovery by monitoring the voltage of the power supply line Vcc, and when it detects it, it operates the pulse generation circuit MMB. The pulse generation circuit MMB outputs a pulse signal having a time width with which the battery voltage can be confirmed by the comparator. The switching means RL is for selectively connecting the battery to the AC power supply side and the comparator side, and is connected to the comparator side while the pulse signal of the pulse generation circuit MMB is valid, and is normally connected to the AC power supply side. Has been done.

The operation of the apparatus configured as above will be described below. FIG. 2 is an explanatory diagram of the operation of the apparatus of FIG. 1, where (A) is the power supply line voltage Vcc, (B) is the voltage monitoring circuit V _IN output, (C) is the pulse generation circuit MMB output, and (D) is the relay RL. Outputs, (E) are comparator CMP outputs, and (F) are storage element RM outputs. When the power is turned on again, the voltage monitoring circuit V _IN outputs a power recovery detection signal after waiting for the power source line voltage Vcc to rise above a certain voltage. At this time, since the power supply voltage Vcc is supplied from the DC-DC converter to the load circuit, the operation is not affected even if the battery is disconnected. Therefore, the pulse generation circuit MMB operates the relay according to the power recovery detection signal to connect the battery from the load circuit side to the comparator. During this time, the comparator checks the backup voltage and records the result in the storage element. Since the load resistance Rf is connected to the comparator side, the battery will be inspected under the same conditions as during backup.

After that, the pulse generation circuit MMB returns the relay RL to connect the battery to the AC power source side. As a result, charging of the battery is started. Then, the memory element has a record of whether the backup voltage is higher or lower than the reference voltage, and can be referred to later.

In the above embodiment, the relay switching is performed only at the time of power recovery detection, but if a separate relay switching signal is provided, it is convenient to check whether backup can be performed by the battery at any time. Become.

[0012]

[Effect of the device]

 As described above, according to the present invention, the battery is disconnected from the AC power supply side immediately after the power is turned on and the backup voltage is measured. Therefore, it is possible to easily inspect whether the load circuit is backed up. During this work, the battery is not charged from the AC power supply side, so the backup voltage can be measured accurately, and the load circuit receives power from the power supply line Vcc during the backup voltage test, so it does not operate. There is a practical effect of not causing any trouble.

[Brief description of drawings]

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

FIG. 2 is an operation explanatory diagram of the apparatus of FIG.

FIG. 3 is a configuration block diagram of a conventional device.

[Explanation of symbols]

 BAT battery CMP comparator RL relay (switching means) RM storage element

Claims (1)

[Scope of utility model registration request] 1. A battery BAT that supplies backup power to a load circuit when the AC power supply is interrupted and is charged by the AC power supply when energized, and the output voltage of the battery are input, and are necessary for backup of the load circuit. A comparator CMP for comparing whether there is a minimum voltage or more, an element RM for storing the output signal of the comparator, a switching means RL for switching and connecting the battery to the comparator and the AC power supply side, and A battery backup circuit comprising: a switching control unit that connects the battery to the comparator by the switching unit at the start of energization and then connects the battery to the AC power source side.