Charger circuit

• US 8,890,485 B2
• Filed: 10/06/2009
• Issued: 11/18/2014
• Est. Priority Date: 10/06/2009
• Status: Active Grant

• Current Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Original Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Inventors: Kung, Nien-Hui, Chu, Kwan-Jen
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): PIGGUSH, AARON C
• Application Number:
  US12/574,035
• Publication Number:
  US 20110080142A1
• Time in Patent Office: 1,869 Days
• Field of Search: 320/134, 320/141, 320/155, 320/159, 320/164
• US Class Current: 320/155
• CPC Class Codes: N/A

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 method to charge a battery by a charger circuit, comprising:

charging the battery by a first charging current and counting a predetermined maximum charging period; and

after the predetermined maximum charging period and the battery has not yet reached a predetermined voltage in the predetermined maximum charging period, charging the battery by a second charging current, the second charging current being a predetermined non-zero constant low current which is lower than the first charging current to determine whether the battery is usable, that it is chargeable by a low rate and is not completely unchargeable.

2. The method of claim 1, wherein the first charging current has a lower limit, and the predetermined non-zero constant low current is a current below the lower limit.

3. The method of claim 1, wherein when the battery is usable, the battery is charged by the predetermined non-zero low current and a voltage of the battery increases.