JPH02261022A - Electric power supply controller - Google Patents

Abstract

PURPOSE:To perform correct voltage detection without being affected by voltage variations at a voltage detection point by providing with a control means to control an ON/OFF state of a circuit by the command from a microcomputer, a comparator to compare the supply voltage with reference voltage and a switching means to change over that reference voltage value. CONSTITUTION:A microcomputer 16 sends V1 to a comparator 15 as a reference voltage value when a motor 19 is OFF. If its result of comparison is 0, it is indicated on a display 17 that a battery is exhausted. When the motor 19 is put to 'ON', a reference voltage value is sent to the comparator 15 before an ON command is issued to the motor 19 and it is checked whether the circuit network is misoperated when the motor 19 is started. If the result of comparison is 0, then the starting of the motor 19 is prohibited. If it is 1, the motor 19 is turned ON. While the motor is ON, a reference voltage value V2 is sent to the comparator 15. The reference voltage value is switched depending on the ON/OFF state of the motor 19. If the result of comparison is 0, then it is indicated on a display 17 that the battery is exhausted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a power supply control device for equipment using a battery as a power source.

BACKGROUND OF THE INVENTION In recent years, electronic devices, including laptop computers, have become increasingly portable, and battery power sources have become indispensable.

By the way, the battery power supply voltage decreases as the device is used, so in order to prevent device malfunction, it is necessary to constantly monitor the power supply voltage and display the voltage level and notify when it is time to replace the battery. is necessary.

A conventional power supply control device will be explained below.

FIG. 3 shows a conventional power supply control device.

In FIG. 3, 31 is a battery, 32 is an internal resistance of the battery,
33 is a voltage detection point, 34 is two resistors for dividing the voltage at the voltage detection point 33, 35 is a divided voltage obtained by dividing the voltage at the voltage detection point 33 by the resistor 34, 36 is a Zener diode, and 37 is a Comparator, 38 is a light emitting diode (hereinafter referred to as LE)
(abbreviated as D), 39 is a circuit network. The operation of the conventional power supply control device configured as described above will be explained.

The output voltage of the Zener diode 36 is always constant regardless of the power supply voltage, and the comparator 37 compares this voltage with a divided voltage 35 obtained by dividing the voltage at the voltage detection point 33 by a resistor 34. When the power supply voltage decreases and the divided voltage 35 becomes lower than the output voltage of the Zener diode 36, the output of the comparator 37 is inverted from low to high. The output voltage lights up the LED to indicate that the battery needs to be replaced.

The voltage that ignores the voltage drop due to the internal resistance of the battery 31 is Vl.
If the current consumption in the internal resistance 32 is R1 and the circuit network 39 is I, the voltage V1 at the voltage detection point 33 is not the voltage V of the battery itself, but the voltage after a voltage drop due to the internal resistance of the battery 32, etc. .

i.e. V1=V-I*R It is.

Problems to be Solved by the Invention However, in the above conventional configuration, there is no ON/OFF in the circuit network.
When the circuit has an OFF state, the circuit has an OFF state.
Because the voltage drop due to internal resistance of the battery changes between the FF state and the ON state, the voltage at the voltage detection point changes.
There is a problem in that battery voltage cannot be detected accurately with a reference voltage value that is always constant. Also, the above circuit is ON
There is also the problem that, in the worst case, the circuit network may malfunction due to a drop in the power supply voltage during this process.

The present invention solves the above-mentioned conventional problems, and even when the circuit network includes a circuit with an ON/OFF state, it is not affected by the voltage change at the voltage detection point due to the ON/OFF operation of the circuit and is accurate. The purpose of the present invention is to provide a power supply control device that can detect voltages.

Means for Solving the Problem In order to solve this object, the power supply control device of the present invention includes a control means for controlling the ON/OFF state of the circuit according to commands from a microcomputer, and a comparison means for comparing the power supply voltage with a reference voltage value. It consists of a voltage regulator and switching means for switching its reference voltage value.

Effect: With the above-described configuration, when the microcomputer turns on the circuit, the voltage can be detected taking into account the internal resistance of the battery by switching the reference voltage value to be compared with the comparator.

Further, by turning on the circuit, it is possible to prohibit the ON operation of the circuit when the power supply voltage is expected to be lower than the operation guaranteed voltage of the circuit network.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a power supply control device in one embodiment of the present invention. In FIG. 1, 11 is a battery, 12 is an internal resistance of the battery, 13 is a voltage detection point, 14 is an A/D converter, 15 is a comparator, 16 is a microcomputer, 17 is a display, -18 is a circuit network, 19 is a motor (circuit with ONlo FF state)
, IA is a control means that performs ON/OFF control of the circuit 19 from a microcomputer.

The operation of the power supply control device of this embodiment configured as described above will be described below. The A/D converter 14 A/D converts the voltage at the voltage detection point 13 and outputs it to the comparator 15. The comparator 15 compares the digital data with the reference voltage value data output from the microcomputer 16,
If the digital data is larger than the reference voltage value, 1 is output to the microcomputer 16, and if it is smaller, 0 is output to the microcomputer 16. The microcomputer 16 detects the battery 11 when the input from the comparator 15 changes from 1 to O.
It determines whether the battery is depleted and indicates whether the battery needs to be replaced or the like on the display F.

When the motor 19 is OFF, the voltage V1 at the voltage detection point 13
is the voltage of the battery itself ignoring the voltage drop due to the internal resistance of the battery, etc., and the current 11 consumed by the battery's internal resistance R1 circuit network 18 is expressed as follows, as described in the conventional example.

V1=V-I 1*R・(1) However, when the motor 19 is ON, the voltage V2 at the voltage detection point 13 is V2=V-(11+I2)*R, assuming that the current consumed by the motor 19 is 12.・It becomes like (2).

Based on equations (1) and (2), the relationship between Vl and v2 is as follows.

V1+I 1*R=V2+ (I 1+I 2)*RV
1=V2+ I 2*R V2=V1-I2*R・(3) As can be seen from equation (3), a voltage difference of ■2*R occurs between vl and ■2, and vl>v2. Therefore, accurate voltage detection cannot be achieved by comparing the voltage at the voltage detection point 13 with a fixed reference voltage value.

Therefore, the microcomputer 16 controls the motor 19 by the control means IA.
When turning ON, lower the reference voltage output from the microcomputer 16 to comparator 15 by I2*R, and then raise I2*R when turning OFF after the ON state. By returning it to its original state, accurate voltage detection can be performed.

I 2 *R can be determined in advance by actual measurement.

Incidentally, the minimum value of the operation guaranteed voltage of the circuit network 18 is assumed to be VO. If the battery continues to be consumed even though the battery replacement indication is displayed on the display 17, and the power supply voltage drops to (VO++2*R) when the motor is OFF, turn on the motor 19. As a result, the power supply voltage may drop I2*R and the circuit network 18 may malfunction.

Therefore, if the microcomputer 16 uses the comparator 15 to monitor whether the power supply voltage is lower than (VO + I 2 * R) before turning on the motor 19, the circuit will be connected when the motor 19 is turned on. 18 can be prevented from malfunctioning by prohibiting the motor 19 from turning on.

FIG. 2 is a processing diagram of the microcomputer 16 in this embodiment. VO, Vl, I2. R is the same as above.

It is also assumed that the comparator 15 outputs 1 if the voltage at the voltage detection point 13 is larger than the reference voltage value, and outputs 0 if it is smaller.

First, the microcomputer 16 uses the comparator 1 when the motor 19 is OFF.
5 as a reference voltage value, the receiver receives the comparison result, and if the result is O, a message is displayed on the display 17 indicating that the battery is exhausted.

When turning on the motor 19, before issuing an ON command to the motor 19, the reference voltage value (VO+I2*R
) to check whether the circuit network malfunctions even if the motor is started. If the comparison result is O, motor starting is prohibited and a display is displayed on the display 15. If the comparison result is 1, the motor 19 is turned on.

While the motor 19 is ON, the reference voltage value V2 is sent to the comparator I5, and the reference voltage value is switched depending on the ON/OFF state of the motor 19.

If the comparison result is O, a message is displayed on the display 17 indicating that the battery is exhausted. The relationship between vl and V2 is V1=V2+I
2*R7- Yes.

When turning off the motor 19, turn off the motor as it is.
Issue FF command. The above is the processing of the microcomputer 16.

As described above, according to this embodiment, the control means controls the ON/OFF state of the circuit according to commands from the microcomputer;
By providing a comparator that compares the power supply voltage with a reference voltage value and a switching means that switches the reference voltage value, accurate voltage detection that is not affected by voltage changes at the voltage detection point can be performed, and ON/OFF Malfunctions of the circuit network caused by a circuit in an OFF state being turned ON can be prevented.

Effects of the Invention As described above, the present invention provides ON/OFF operation using a battery as a power source.
In a circuit network that includes circuits that have states, the circuits that have ON/OFF states can be turned ON/OFF by commands from the microcomputer.
By providing a control means for controlling F, a comparator for comparing the power supply voltage with a reference voltage value, and a switching means for switching the reference voltage value, voltage drop due to internal resistance of the battery etc. due to ON/OFF of the above circuit can be reduced. It is possible to perform accurate voltage detection without being affected, and when it is predicted that turning on the above circuit will cause the voltage to drop below the guaranteed operation voltage of the circuit, the ON operation of the circuit that has an ON/OFF state can be controlled as described above. It can be prohibited by means, and its practical effects are great.

[Brief explanation of drawings]

FIG. 1 shows a power supply control device in one embodiment of the present invention;
The figure is a processing diagram of a microcomputer in an embodiment of the present invention.
The figure shows a conventional power supply control device. 11...Battery, 12...Battery internal resistance, 13
...Voltage detection point, 14...A/D converter,
15... Comparator, 16... Microcomputer, 17
...Display device, 18...Circuit network, 19...
Circuits with ON/OFF status, IA: Control means that performs ON/OFF control of 19 circuits from a microcomputer.

Claims (2)

[Claims] (1) Turn ON/OFF the circuit according to commands from the microcomputer
A control means for controlling the state, a comparator for comparing the power supply voltage with a reference voltage value, and a switching means for switching the reference voltage value, the reference voltage value being input to the comparator depending on the ON/OFF operating state of the circuit. A power supply control device characterized by switching. (2) The power supply control device according to claim 1, wherein the ON operation of the circuit is prohibited when the power supply voltage is below a certain voltage value.