JPH09274059A - Voltage detection circuit for auxiliary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a voltage detection circuit which prevents data from being lost due to the supply shortage of a data holding voltage due to the consumption or the like of an auxiliary battery when the main battery of a memory card is replaced by a method wherein a voltage detector or the like which detects the voltage of the auxiliary battery is installed. SOLUTION: When a main battery holder 31 is mounted on a body, a switch botton 63 is pressed to a protrusion part 39a, and a switch 61 is set to an OFF state. When the main battery holder is taken out form the body, knob parts 31a, 31b are sandwiched so as to be moved to the center, the protrusion part 39a is moved to the center, the switch botton 63 is released from its pressure, and the switch 61 is set to an ON state. When the switch 61 is turned pn, the voltage of an auxiliary battery 25 is detected by a voltage detector, and an LED 59 emits light when the voltage of the auxiliary battery 25 is lower than a prescribed voltage. That is to say, when such a function is installed at a memory card, the voltage of the auxiliary battery 25 can be detected, and it is possible to prevent data in a volatile memory form being erased when a main battery 19 is replaced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage detection circuit for detecting the voltage of a backup battery, and more particularly to a main battery for supplying a data holding voltage to a volatile memory integrated circuit when not mounted on an information processing device, The present invention relates to detection of a voltage of an auxiliary battery in a device including an auxiliary battery that backs up a main battery, such as a memory card.

[0002]

2. Description of the Related Art A conventional memory card equipped with a volatile memory integrated circuit such as SRAM (static RAM) is
When connected to the information device, the power supply voltage for the data access and holding operation is supplied from the information device, and when not connected to the information device, the power supply voltage is supplied by the internal battery to hold the data in the memory. Supplied. Many of these memory cards also have an auxiliary battery for supplying a voltage to the memory integrated circuit even when the internal battery (main battery) is replaced.

FIG. 5 shows a circuit diagram of a power supply section of a memory card having a conventional auxiliary battery. The power supply unit shown in FIG. 5 includes a power supply integrated circuit (hereinafter referred to as a power supply IC) 13 connected to an internal power supply line 11 that supplies a power supply voltage to the internal circuit, and a parallel circuit including a resistor 15 and a diode 17. The main battery 19 is connected to the power supply IC 13 via the auxiliary battery 25 connected to the internal power supply line 11 via the resistor 21 and the changeover switch 23.

When the memory card is connected to the information equipment, the power supply IC 13 detects the power supply voltage from the information equipment and supplies the internal circuit with the power supply voltage from the information equipment. On the other hand, when the memory card is not connected to the information device,
The voltage from the main battery 19 is supplied to the internal circuit. Main battery 1
When replacing 9, the changeover switch 23 is turned on,
A voltage for holding data is supplied to the internal circuit from the auxiliary battery 25.

FIG. 6 shows a mounted state inside a memory card having the circuit of FIG. 6, the memory card 27 includes a main battery 19, an auxiliary battery 25, a module substrate 29, a main battery holder 31, an auxiliary battery holder 33, a rotary switch 35, and contacts 37a and 37b of the rotary switch 35. Equipped with. This rotary switch 35
Corresponds to the changeover switch 23 in FIG. Main battery holder 3
1 is provided with knobs 31a and 31b for use when the main battery holder 31 is pulled out. Contact 37
Reference numerals a and 37b are contacts for switching the voltage supply source between the main battery 19 and the auxiliary battery 25. Main battery holder 31
Is a protrusion 39 provided on the knobs 31a and 31b.
The a and 39b are locked to the main body by engaging with the recess 41 of the main body.

When the memory card is not connected to the information device, the rotary switch 35 is normally connected to the contact 37.
The data holding voltage is supplied from the main battery 19 as a backup power source by contacting a. When switching from the main battery to the auxiliary battery, the rotary switch 35 contacts the contact 37b, and the data holding voltage is supplied from the auxiliary battery 25 as a backup power supply. When pulling out the main battery holder 31 from the main body, as shown in FIG. 7, the knob portions 31a and 31b are pinched with fingers and moved to the center to project the protrusions 39a, 3b.
9b is released from the recess 41 and can be removed. At this time, the rotation switch 35 is rotated by the main battery holder 31 and comes into contact with the contact 37b, the backup power source is switched from the main battery 19 to the auxiliary battery 25, and the data holding voltage is supplied. In this way, the backup power source is switched from the main battery 19 to the auxiliary battery 25 by the rotary switch 35.

[0007]

However, in such a memory card, the voltage of the main battery 19 can be detected from the voltage detection terminal of the connected information equipment.
The voltage of the auxiliary battery 25 could not be detected from the outside. Therefore, when the voltage of the auxiliary battery 25 is low, or when the auxiliary battery 25 is not attached, a sufficient voltage as a data holding voltage for the memory integrated circuit is obtained when the main battery 19 is replaced. There was a problem that data was lost because it was not supplied.

The present invention has been made to solve the above problems, and an object of the present invention is to erase data in a memory card due to insufficient supply of a data holding voltage due to exhaustion of an auxiliary battery when replacing a main battery. It is to provide a voltage detection circuit for preventing the above.

[0009]

In an auxiliary battery voltage detection circuit according to the present invention, a main battery for supplying a data holding voltage as a backup power source to a memory integrated circuit,
In a device including an auxiliary battery that supplies a power supply voltage instead of the main battery when the main battery is replaced, a voltage detection unit that detects the voltage of the auxiliary battery and outputs a detection signal,
Warning means for issuing a predetermined warning when the voltage of the auxiliary battery is lower than a predetermined voltage based on the detection signal.

Preferably, in the voltage detection circuit for the auxiliary battery, the warning means includes a light emitting means, and a control means for causing the light emitting means to emit light when the voltage of the auxiliary battery is lower than a predetermined voltage based on the detection signal. Equipped with. The light emitting means is composed of, for example, a light emitting diode and emits light to warn the user of the voltage drop of the auxiliary battery.

Preferably, in the auxiliary battery voltage detection circuit, the warning means controls the sounding means and the sounding means to output a sound based on the detection signal when the voltage of the auxiliary battery is lower than a predetermined voltage. And means. The sounding means is composed of, for example, a speaker and an oscillating circuit, and outputs a sound to warn the user of the voltage drop of the auxiliary battery.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Embodiment 1 FIG. FIG. 1 shows a circuit diagram of a power supply unit of the memory card according to the first embodiment. The memory card of the present embodiment notifies the detection result of the voltage of the auxiliary battery by causing the light emitting diode to emit light when the voltage of the auxiliary battery is lower than the predetermined voltage when the main battery is replaced. FIG.
The circuit shown in Fig. 5 is the same as the conventional circuit shown in Fig.
The auxiliary battery voltage detection circuit 51 for detecting the voltage of No. 5 is further provided. The auxiliary battery voltage detection circuit 51 includes a switch 53 having one end connected to the anode of the auxiliary battery 25, and a voltage detector 55 having an input terminal connected to the other end of the switch 53.
, A NAND gate 57 in which the internal power supply line 11 and the output terminal of the voltage detector 55 are connected to the input terminal, and a light emitting diode 59 connected to the output terminal of the NAND gate 57. The operation of the auxiliary battery voltage detection circuit 51 will be described below.

When the switch 53 is closed, the voltage of the auxiliary battery 25 is input to the voltage detector 55. The voltage detector 55 compares the input voltage with a predetermined voltage, which is the lowest voltage that enables data retention, and outputs a control signal of "H (High level signal)" when the input voltage is lower than the predetermined voltage. The NAND gate 57 inputs the signal of “H (High level signal)” from the power supply line 11. Then, the control signal “H” input from the voltage detector 55,
A NAND operation is performed on the signal “H” input from the power supply line 11 and a power supply voltage is supplied to the light emitting diode 59 to cause the light emitting diode 59 to emit light. Voltage detector 55
Outputs a control signal of "L" when the input voltage is higher than the predetermined voltage, the NAND gate 57 does not supply the power supply voltage to the light emitting diode 59 and the light emitting diode 59 does not emit light. In this way, the auxiliary battery voltage detection circuit 5
1 detects the voltage of the auxiliary battery 25 and causes the light emitting diode 59 to emit light when the voltage of the auxiliary battery 25 is lower than a predetermined voltage to notify the user of the voltage drop.

FIG. 2 shows the configuration when the main battery 19, the auxiliary battery 25, the switch 53 and the like of the circuit of FIG. 1 are arranged in the card body. The memory card of FIG. 2 is different from the memory card of FIG. 6 in further including a push switch 61, a switch button 63, and a light emitting diode 59. The push switch 61 is the switch 53 of FIG.
Is equivalent to The push switch 61 is turned on / off by being pressed by the switch button 63, and is turned off when pressed. Switch button 63
Is pressed by the protrusion 39 a of the main battery holder 31. The operation of the switch 61 will be described below.

In FIG. 2, when the main battery holder 31 is mounted on the main body, the switch button 63 is pushed by the protrusion 39a of the main battery holder 31, so that the switch 6
1 is turned off. When the main battery holder 31 is taken out from the main body, the knobs 31a and 31b are sandwiched and brought closer to the center, so that the protrusion 39a is closer to the center and the switch button 63 is released from being pressed, as shown in FIG. 61 is turned on. When the switch 61 is turned on, the voltage of the auxiliary battery 25 is detected based on the above-described operation, and when the voltage of the auxiliary battery 25 is lower than the predetermined voltage, the light emitting diode 59 emits light. That is, by providing such a mechanism in the memory card body, it is possible to detect the voltage of the auxiliary battery 25 and prevent accidentally erasing data in the volatile memory when the main battery 19 is replaced.

Embodiment 2 FIG. FIG. 4 is a circuit diagram of the power supply unit of the memory card according to the second embodiment. The memory card of the present embodiment notifies the detection result of the voltage of the auxiliary battery by emitting a warning sound from the speaker when the voltage of the auxiliary battery is lower than the predetermined voltage. The circuit shown in FIG. 4 is different from the circuit shown in FIG. 1 in that an oscillation circuit 73 and a speaker 75 are provided instead of the light emitting diode 59. The operation of the circuit shown in FIG. 4 will be described below.

When the switch 53 is closed, the voltage of the auxiliary battery 25 is detected as described above, and the voltage is supplied from the NAND gate 57 to the oscillation circuit 73 based on the detection result. That is, when the voltage of the auxiliary battery 25 is lower than the predetermined voltage, the voltage is supplied to the oscillation circuit, and the speaker 75 outputs a warning sound by the output signal from the oscillation circuit. On the other hand, when the voltage of the auxiliary battery 25 is equal to or higher than the predetermined voltage, no voltage is supplied to the oscillation circuit, so the speaker 75
No warning sound is output from. In this way, the auxiliary battery voltage detection circuit 71 detects the voltage of the auxiliary battery 25, and the speaker 7 is detected when the voltage of the auxiliary battery 25 is lower than the predetermined voltage.
By outputting a warning sound from 5, the user is notified of the voltage drop. Further, in the structure diagram of FIG. 2, by providing the speaker 75 instead of the light emitting diode 59,
The memory card of this embodiment can be configured.

As described above, according to the memory card of the present embodiment, by detecting the voltage of the auxiliary battery before replacing the main battery, when the voltage of the auxiliary battery is lower than the voltage at which data can be held, the optical card Alternatively, a sound can be used to warn the user.

Although the voltage detection circuit of the first or second embodiment detects the voltage of the auxiliary battery when the main battery is replaced, the voltage detection circuit of the present invention is not limited to this, and the voltage detection circuit of the auxiliary battery is always detected. The warning may be issued when the detection voltage becomes equal to or lower than a predetermined voltage.

[0021]

According to the auxiliary battery voltage detection circuit of the present invention, the auxiliary battery voltage is detected, and when the detected voltage is lower than a predetermined voltage, a predetermined warning means such as light or sound is used. Since the user is informed, it is possible to prevent data loss when the main battery is replaced due to exhaustion of the auxiliary battery or non-attachment of the auxiliary battery.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a power supply unit of a memory card according to a first embodiment.

FIG. 2 is a structural diagram of the memory card according to the first embodiment.

FIG. 3 is a structural diagram of the memory card according to the first embodiment.

FIG. 4 is a circuit diagram of a power supply unit of the memory card according to the second embodiment.

FIG. 5 is a circuit diagram of a power supply unit of a conventional memory card.

FIG. 6 is a structural diagram of a conventional memory card.

FIG. 7 is a structural diagram of a conventional memory card.

[Explanation of symbols]

11 internal power supply line, 13 power supply IC, 15, 21 resistance, 17 diode, 19 main battery, 23 changeover switch, 25 auxiliary battery, 27 memory card body, 29
Module board, 31 Main battery holder, 31a, 31
b knob, 33 auxiliary battery holder, 35 rotation switch, 37a, 37b contact, 39a, 39b protrusion,
41 recessed portion, 51 auxiliary voltage detection circuit, 53 switch, 55 voltage detector, 57 NAND gate, 59
Light emitting diode (LED), 61 push switch, 6
3 switch buttons, 73 oscillator circuits, 75 speakers.

Claims (3)

[Claims] 1. An apparatus comprising: a main battery for supplying a data holding voltage as a backup power supply to a memory integrated circuit; and an auxiliary battery for supplying a power supply voltage instead of the main battery when the main battery is replaced, A voltage detection unit that detects the voltage of the auxiliary battery and outputs a detection signal, and a warning unit that issues a predetermined warning when the voltage of the auxiliary battery is lower than a predetermined voltage based on the detection signal are provided. The auxiliary battery voltage detection circuit. 2. The voltage detection circuit for an auxiliary battery according to claim 1, wherein the warning means emits light from the light emitting means when the voltage of the auxiliary battery is lower than a predetermined voltage based on the light emitting means and the detection signal. A voltage detection circuit for the auxiliary battery, which includes a control means for controlling the voltage. 3. The voltage detecting circuit for the auxiliary battery according to claim 1, wherein the warning means outputs a sound to the sounding means when the voltage of the auxiliary battery is lower than a predetermined voltage based on the sounding means and the detection signal. A voltage detection circuit for an auxiliary battery, comprising: