JP2806658B2 - Battery low voltage detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery low voltage detection circuit, and more particularly to a method for detecting an open state of a connection terminal of a battery.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional battery low voltage detection circuit. A negative terminal 2 for connecting a battery, a positive terminal 3 and the input of the comparator 6 are connected to G even when the battery connection terminal is open.
A pull-down resistor 9 for setting the ND potential, a reference voltage 4 connected to one input of the comparator 6, and a GND potential when the tenth input voltage is lower than the one input voltage, and a Vcc when the tenth input voltage is higher than the one input voltage.
It has a comparator 6 that outputs a potential, and an output terminal 10 that is the output of the comparator 6.

[0003]

In the conventional battery low voltage detection circuit, a pull-down resistor 6 for setting the input of the comparator 6 to the GND potential is required even when the connection terminal of the battery is open. There is a problem that the battery current is always consumed.

An object of the present invention is to provide a battery low-voltage detection circuit that can detect the opening of a battery connection terminal without wasting battery current during a battery voltage test.

[0005]

The battery low voltage detection circuit according to the present invention is connected to a first negative terminal connected to GND and an input of a NOT gate pulled up to Vcc by a pull-up resistor. A second negative terminal independent of the negative terminal of the comparator, a positive terminal connected to one input of the comparator, a reference voltage connected to the other input of the comparator, an output of the comparator and a NOT gate. And an AND gate connected to the output.
When the output of the D gate is at the GND potential, the first and second
Open of the negative terminal of the battery or low voltage of the battery is detected.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention. A negative terminal 2 connected to GND; a negative terminal 1 connected to an input of a NOT gate 7 which is pulled up to Vcc by a pull-up resistor 5; a positive terminal 3 connected to an input of a comparator 6; The reference voltage 4 connected to the other input, the output of the comparator 6 and NO
And an AND gate 8 to which the output of the T gate 7 is connected.

When the battery is connected, the negative terminal 1 and the negative terminal 2 are connected via the negative terminal of the battery, and the NOT gate 7 is connected.
Is supplied with a GND potential. NOT gate 7 outputs the Vcc potential and is input to AND gate 8. Therefore A
The output of the comparator 6, which is the other input of the ND gate 8, is output to the output terminal 10 as it is. When the voltage of the battery connected to the positive terminal 3 is lower than the reference voltage 4, GND
When the potential is high, the Vcc potential is output from the comparator 6 when the potential is high.

When the battery is not connected and the negative terminal 1 or 2 is open, the input of the NOT gate 7 is set to the Vcc potential by the pull-up resistor 5, so that the output of the NOT gate 7 is GND.
Potential. Therefore, the AND gate 8 outputs the GND potential to the output terminal 10 so that the opening of the connection terminal can be detected.

[0010]

As described above, according to the present invention, two negative terminals of connection terminals are provided, the negative terminal 2 and the negative terminal 1 are connected through the negative terminal of the battery terminal, and the comparator 6 is connected through the NOT gate 7. Since the output is input to the AND gate 8 together with the output, and the output of the AND gate 8 is used for the output terminal 10, when the connection terminal is open, the input of the NOT gate 7 becomes the Vcc potential by the pull-up resistor 5, so that the output is GND.
And the GND potential from the AND gate 8 to the output terminal 1
0 is output to detect the opening of the detection terminal, and there is no need to connect a pull-down resistor to the positive terminal 3, so that there is an effect that the current consumption of the battery can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a diagram of a conventional low voltage detection circuit.

[Explanation of symbols]

 1, 2 Negative terminal 3 Positive terminal 4 Reference voltage 5 Pull-up resistor 6 Comparator 7 NOT gate 8 AND gate 9 Pull-down resistor 10 Output terminal

Claims (1)

(57) [Claims] A first negative terminal connected to GND;
NOT pulled up to Vcc by pull-up resistor
A second negative terminal connected to the input of the gate and independent of the first negative terminal; a positive terminal connected to one input of the comparator; a reference voltage connected to the other input of the comparator; Comparator output and NOT
And an AND gate connected to an output of the gate, wherein when the output of the AND gate is at the GND potential, opening of the first and second negative terminals or low voltage of the battery is detected. Voltage detection circuit.