Battery pack

Abstract

A battery pack is disclosed. The battery pack includes a battery; a current detecting unit which detects charging and discharging currents of the battery and outputs an analog signal corresponding to the charging and discharging currents; a modulating unit which modulates the analog signal to be a PDM (pulse density modulation) signal by applying a PDM modulation to the analog signal; a memory in which a conversion program for converting the PDM signal into PCM (pulse code modulation) data and a remaining battery charge calculating program for calculating a remaining battery charge by accumulating the PCM data are stored; and a CPU, which converts the PDM signal into the PCM data which are digital data by being supplied the PDM signal from the modulating unit while executing the conversion program stored in the memory, and calculates the remaining battery charge by accumulating the PCM data while executing the remaining battery charge calculating program stored in the memory.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a battery pack according to a first embodiment of the present invention;

FIG. 2 is an exploded perspective view of the battery pack shown in FIG. 1;

FIG. 3 is a perspective view of a circuit board shown in FIG. 1;

FIG. 4 is a block diagram showing a fuel gauge IC according to the first embodiment of the present invention;

FIG. 5 is a block diagram showing a sigma-delta modulator shown in FIG. 4;

FIG. 6 is a diagram showing programs stored in a ROM of a memory shown in FIG. 4;

FIG. 7 is a flowchart showing processes in a CPU shown in FIG. 4;

FIG. 8 is a block diagram showing a decimation filter formed of hardware;

FIG. 9 is a flowchart showing a digital filter process which is executed by the CPU in step S1-3 shown in FIG. 7 in detail;

FIG. 10 is an operations chart according to the first embodiment of the present invention;

FIG. 11 is a block diagram showing a battery pack according to a second embodiment of the present invention; and

FIG. 12 is a diagram showing a connection of a battery pack shown in FIG. 11 with a mobile electronic device.

Claims

1. A battery pack, comprising: a battery;a current detecting unit which detects charging and discharging currents of the battery and outputs an analog signal corresponding to the charging and discharging currents;a modulating unit which modulates the analog signal to be a PDM (pulse density modulation) signal by applying a PDM modulation to the analog signal;a memory in which a conversion program for converting the PDM signal into PCM (pulse code modulation) data and a remaining battery charge calculating program for calculating a remaining battery charge by accumulating the PCM data are stored; anda CPU, which converts the PDM signal into the PCM data which are digital data by being supplied the PDM signal from the modulating unit while executing the conversion program stored in the memory, and calculates the remaining battery charge by accumulating the PCM data while executing the remaining battery charge calculating program stored in the memory.

2. The battery pack as claimed in claim 1, wherein: the CPU intermittently executes the conversion program, loads the PDM signal from the modulating unit, and converts the PDM signal into the PCM data.

3. The battery pack as claimed in claim 1, further comprising: a voltage detecting unit which detects a voltage of the battery;a temperature detecting unit which detect ambient temperature of the battery pack; anda selecting unit which selects one of analog signals detected from the current detecting unit, the voltage detecting unit, and the temperature detecting unit; whereinthe remaining battery charge calculating program corrects the remaining battery charge by using the PCM data of the voltage detected by the voltage detecting unit and the PCM data of the temperature detected by the temperature detecting unit when the remaining battery charge calculating program accumulates the PCM data of the charging and discharging currents.

4. The battery pack as claimed in claim 1, wherein: the modulating unit is a sigma-delta modulator.

5. The battery pack as claimed in claim 1, wherein: the current detecting unit, the modulating unit, the memory, and the CPU are integrated into one semiconductor integrated circuit.