PULSE CHARGING APPARATUS

Abstract

A pulse charger perform fine control of a charging current according to a battery voltage. The pulse charger includes a switch that turns a charging current from an external power supply on and off. A current detector detects charging current using a current detection resistor. An averaging section averages the output of the current detector. A reference voltage generator generates a reference signal. A comparison section compares an output voltage from the averaging section with the reference signal. A controller controls the switch section based on the output of comparison section. The comparison section includes a comparator that has a hysteresis width. The comparison section outputs an inverse signal between reference voltage and the hysteresis width. The controller performs on/off control of the switch section based on an inverse signal from the comparator and sets an average value of the charging current to a target constant value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in conjunction with the accompanying drawing wherein one example is illustrated by way of example, in which:

FIG. 1 is a block diagram showing the configuration of an electronic device that uses a battery pack containing a conventional pulse charging apparatus;

FIG. 2 is a block diagram showing the configuration of a pulse charging apparatus according to Embodiment 1 of the present invention;

FIG. 3 is a circuit diagram showing the detailed configuration of a pulse charging apparatus according to above Embodiment 1;

FIG. 4 is a characteristic graph showing the output characteristic of an external power supply of a pulse charging apparatus according to above Embodiment 1;

FIG. 5 shows operational waveform diagrams of each section of a pulse charging apparatus according to above Embodiment 1;

FIG. 6 is a block diagram showing the configuration of a pulse charging apparatus according to Embodiment 2 of the present invention;

FIG. 7 is a circuit diagram showing the detailed configuration of a pulse charging apparatus according to above Embodiment 2; and

FIG. 8 shows operational waveform diagrams of each section of a pulse charging apparatus according to above Embodiment 2.

Claims

1. A pulse charging apparatus comprising: a switch section that turns a charging current from a direct-current source on and off;a current detection section that detects the charging current;an averaging section that averages output of the current detection section;a reference signal generation section that generates a reference signal;a comparison section that compares output of the averaging section with the reference signal; anda control section that controls the switch section based on output of the comparison section.

2. A pulse charging apparatus comprising: a switch section that turns a charging current from a direct-current source on and off;a current detection section that detects the charging current;a voltage averaging section that smoothes output of the current detection section;a triangular wave generation section that generates a triangular wave signal;a comparison section that compares output of the voltage averaging section with the triangular wave signal; anda control section that controls the switch section based on output of the comparison section.

3. The pulse charging apparatus according to claim 1, wherein: the comparison section is composed of a comparator having a hysteresis width, and outputs an inverse signal between the reference voltage and the hysteresis width; andthe control section performs on/off control of the switch section based on the inverse signal from the comparator, and makes a charging current from the direct-current source a constant current as an average charging current.

4. The pulse charging apparatus according to claim 2, wherein: the comparison section compares a signal smoothed by the voltage averaging section with the triangular wave signal and outputs an inverse signal; andthe control section performs on/off control of the switch section based on the inverse signal from the comparator, and makes a charging current from the direct-current source a constant current as an average charging current.

5. The pulse charging apparatus according to claim 2, wherein the voltage averaging section has an integrating circuit that smoothes output of the voltage detection section.

6. The pulse charging apparatus according to claim 1, further comprising a battery voltage detection section that detects a battery voltage of a secondary battery; wherein the control section performs control that turns the switch section off when a predetermined battery voltage is detected by the battery voltage detection section.