JPH09130983A - Battery charge control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically switch DC output voltage of an AC-DC converter part based on identification, by identifying a kind of a battery to be charged. SOLUTION: Cell voltage of a battery is detected by a battery discrimination circuit 20, to identify what kind the battery is. Based on this identification result, the battery identification circuit 20 controls a variable type switching regulator 11 and outputs DC voltage suited for a battery 3 intended to be charged. On the other hand, a microcomputer 10, detecting the cell voltage through a voltage detection circuit 9, controls a control switch 5 and supplies charge control voltage to the battery 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery charge control device for charging a battery of a mobile phone, for example.

[0002]

2. Description of the Related Art Batteries used in portable devices such as mobile phones are roughly classified into lithium ion batteries and Ni- batteries.
There are three types of batteries, MH batteries and dry batteries. Among them, those that can be charged are lithium ion batteries and Ni-MH batteries.

The charging of the lithium ion battery is a constant voltage charging, and the charging is performed so that the battery voltage does not exceed 4.10 V, and when the charging current becomes 100 mA or less, it is regarded as a full charge and the charging is completed.

On the other hand, the Ni-MH battery performs pulse charging. That is, at the beginning of charging when the battery voltage is low, the battery voltage is increased by operating in the quick charge mode of full on for 55 seconds and off for 5 seconds. When the battery gradually approaches full charge, N
A feature of the i-MH battery is that the battery voltage eventually begins to decrease after passing the peak of increase. At this time, a point where the fall width is generally 30 mV or more is detected and the battery is fully charged. This point detection is called ΔV detection. ΔV detection is generally around 5.5V, and after ΔV detection, the trickle charge mode of full on for 10 seconds and off for 50 seconds is entered.

An example of a conventional battery charge control device of this type is shown in FIG. In FIG. 2, 1 is a main body of the charging device, 2 is an AC-DC converter, and 3 is a battery to be charged. The charging device main body 1 has a charging circuit 6 having a protection diode 4 and a control switch 5, one end of which is connected to the DC output end of the AC-DC converter 2 and the other end of which is connected to the terminal of the battery 3, and a resistor 7, A voltage detection circuit 9 composed of a voltage dividing circuit 8 for detecting the cell voltage of the battery 2, and a microcomputer (hereinafter referred to as a microcomputer) 10 for controlling the control switch 5 according to an output signal of the voltage detection circuit 9. Is equipped with.
The AC-DC converter 2 is composed of a variable switching regulator 11, and the battery 3 is composed of a battery cell 12, a protection circuit 13, and a protection resistor 14.

In the battery charge control device having the above structure, for example, when charging a lithium ion battery, the cell voltage taken out from the battery cell 12 through the protection resistor 14 is divided by the resistors 7 and 8 of the voltage detection circuit 9, and the detection signal The microcomputer 10
To enter. The microcomputer 10 controls the control switch 5 based on the output signal, and performs constant voltage charging so that the charge control voltage does not exceed 4.10V.

[0007]

However, as described above, in the case of charging control of two batteries having different properties,
When the output of the switching regulator 11 is set to 7V, for example, it is suitable for the ΔV detection of the Ni-MH battery, but in the case of the lithium-ion battery, 4.10V control is performed, so that a loss voltage of 3V is generated and the charging circuit during charging 6 side heats up. Further, when the output of the switching regulator 11 is set to 5V, it is suitable for 4.10V control of a lithium ion battery, but there is a problem that the ΔV of a Ni-MH battery cannot be detected.

The present invention solves the above-mentioned problems of the prior art. When the battery is charged, the type of the battery is identified, and the DC output voltage of the AC-DC converter is automatically determined based on the identification. An object of the present invention is to provide a battery charge control device that is switched to.

[0009]

In order to achieve the above object, a battery charging control device of the present invention comprises a variable power supply device for converting an AC power supply voltage into a desired DC voltage and a variable power supply device at one end. A charging circuit having a control switch, the other end of which is connected to the DC output terminal and the other terminal of the battery, a voltage detection circuit for detecting the cell voltage of the battery, and a charging circuit based on the output signal of the voltage detection circuit From a microcomputer that controls the control switch and a battery identification circuit that identifies the type of battery to be charged from the cell voltage of the battery and sets the DC output of the variable power supply unit to a voltage suitable for charging the identified battery. Composed.

According to the above construction, the battery identification circuit identifies the type of battery to be charged from the cell voltage of the battery, and sets the DC output of the variable power supply unit based on the identification signal.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a battery charge control device according to an embodiment of the present invention, and the same functional parts as those in FIG. 2 are denoted by the same reference numerals. That is, 1 is a charging device main body, 2 is an AC-DC converter, 3 is a battery for charging, 4 is a protection diode, 5 is a control switch, 6 is a charging circuit, 7 and 8 are resistors, 9 is a voltage detection circuit,
Reference numeral 10 is a microcomputer, 11 is a variable switching regulator, 12 is a battery cell, 13 is a protection circuit, and 14 is a protection resistor. Reference numeral 20 is a feature of the present invention, which identifies the type of the battery 3 to be charged from the cell voltage, and sets the DC output of the variable switching regulator 11 to a voltage suitable for charging the identified battery. Circuit.

Next, the charging operation of the battery charge control device in the above embodiment will be described. First, the cell voltage is taken out from the battery cell 12 through the protection resistor 14. The battery identification circuit 20 detects the voltage and identifies what kind of battery the battery to be charged is. The battery identification circuit 20
The variable switching regulator 11 is controlled based on the identification result, and when the battery to be charged is a lithium ion battery, the output voltage is set to, for example, DC 5V.

On the other hand, the cell voltage is divided by the resistors 7 and 8 of the voltage detection circuit 9, and the signal corresponding to the cell voltage is sent to the microcomputer.
Entered in 10. Based on the signal, the microcomputer 10 calculates so that the battery 3 has a predetermined charge control voltage, and sends a charge command signal to the control switch 5. Control switch 5
Based on the charge command signal, will perform constant voltage charging so as not to exceed 4.10V.

[0014]

As described above, according to the present invention,
Since the output voltage of the AC-DC converter is automatically set according to the type of battery to be charged, it is possible to always perform optimal charging without erroneous operation.

[Brief description of the drawings]

FIG. 1 is a block diagram of a battery charge control device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional battery charge control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Charging device main body part 2 ... AC-DC conversion part 3
... Battery, 4 ... Protection diode, 5 ... Control switch, 6 ... Charging circuit, 7,8 ... Resistance, 9 ... Voltage detection circuit, 10 ... Microcomputer, 11 ... Variable switching regulator, 12 ... Battery cell, 20 ... Battery identification circuit.

Claims (1)

[Claims] 1. A variable power supply device for converting an AC power supply voltage into a desired DC voltage, and one end of the variable power supply device DC
A charging circuit having a control switch, the other end of which is connected to the battery terminal, and a voltage detection circuit for detecting the cell voltage of the battery, and the charging circuit of the charging circuit based on the output signal of the voltage detection circuit. The microcomputer for controlling the control switch and the type of the battery to be charged are identified based on the cell voltage of the battery, and D of the variable power supply device is identified.
A battery charge control device comprising: a battery identification circuit that sets the C output to a voltage suitable for charging the identified battery.