Charger Circuit

• US 20110080142A1
• Filed: 10/06/2009
• Published: 04/07/2011
• Est. Priority Date: 10/06/2009
• Status: Active Grant

• Current Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Original Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Inventors: Chu, Kwan-Jen, Kung, Nien-Hui
• Granted Patent: US 8,890,485 B2
• Time in Patent Office: Days
• US Class Current: 320/159
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters

Abstract

A charger circuit comprising: a charging path coupled between an input voltage and a battery; a power switch on the charging path; a switch control circuit controlling the power switch; a timer counting a charging period; and a low current control circuit issuing a signal to the switch control circuit to control the power switch such that a charging current is maintained to be a predetermined low current when the timer counts to a predetermined maximum charging period.

Claims

1. A charger circuit comprising:

a charging path coupled between an input voltage and a battery;

a power switch on the charging path;

a switch control circuit controlling the power switch;

a timer counting a charging period; and

a low current control circuit issuing a signal to the switch control circuit to control the power switch such that a charging current to the battery becomes a predetermined low current after the timer counts to a predetermined maximum charging period.

2. The charger circuit of claim 1, wherein the switch control circuit controls the power switch according to information related to a voltage of the battery and information related to the charging current.

3. The charger circuit of claim 1, further comprising an oscillator whose frequency is changed according to the charging current, and wherein the timer counts the charging period according to the frequency of the oscillator.

4. The charger circuit of claim 3, wherein the oscillator receives information related to the charging current from the switch control circuit.

5. The charger circuit of claim 1, wherein the power switch is a power switch in a power converter.

6. The charger circuit of claim 5, wherein the power converter includes one of the following circuits:

synchronous buck power converter, synchronous boost power converter, synchronous buck-boost power converter, synchronous inverter power converter, fly-back power converter, asynchronous buck power converter, asynchronous boost power converter, asynchronous buck-boost power converter, and asynchronous inverter power converter.

7. The charger circuit of claim 1, wherein the predetermined low current is a current below a lower limit of a normal charging current.

8. The charger circuit of claim 1, wherein the switch control circuit turns off the power switch after the battery is charged by the predetermined low current for a predetermined period.

9. The charger circuit of claim 1, wherein the maximum charging period is set externally from outside of the circuit.