Charging apparatus and charging current detecting circuit thereof

• US 20050007064A1
• Filed: 06/30/2004
• Published: 01/13/2005
• Est. Priority Date: 07/07/2003
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Matsuda, Shoji
• Granted Patent: US 7,382,108 B2
• Time in Patent Office: Days
• US Class Current: 320/103
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries

Abstract

A charging apparatus and a charging current detecting circuit thereof are disclosed in which it is possible to implement an electric circuit with little voltage loss by using an operational amplifier of low cost. A detecting resistor is disposed at the power voltage side of the downstream side of a power supply. The charging apparatus further includes an auxiliary power means for generating an auxiliary voltage to supplement the voltage limited to the range of an input voltage of the operational amplifier.

Claims

1. A charging apparatus comprising:

a power supply for supplying a charging current to a secondary battery;

a detecting resistor disposed at a downstream side of the power supply for detecting the charging current; and

an operational amplifier for applying a voltage from the power supply,

wherein the detecting resistor is disposed at a power voltage side of the downstream side of the power.

2. The charging apparatus according to claim 1, further comprising:

auxiliary power means for generating an auxiliary voltage to supplement a voltage limited to the range of an input voltage of the operational amplifier,

wherein the auxiliary power means comprises;

signal generating means for generating a signal containg an alternating current component;

an AC coupling capacitor for AC-coupling a signal output from the signal generating means;

a first diode for clamping the AC-coupled signal to the power voltage; and

a second diode disposed at a downstream side of the AC-coupling capacitor and first diode for rectifying a signal.

3. A charging current detecting circuit disposed in a charging apparatus having an operational amplifier for applying a voltage from a power supply, in which a charging current is supplied from the power supply to a secondary battery and, comprising:

a detecting resistor for detecting the charging current,

wherein the detecting resistor is disposed at a power voltage side of a downstream side of the power supply.

4. The charging current detecting circuit according to claim 3, further comprising:

auxiliary power means for generating an auxiliary voltage to supplement the voltage limited to the range of an input voltage of the operational amplifier.