Patent ID: 7652451
Filing Date: 2010-01-26
Classification: H02J

Abstract:
1. A charging control circuit for charging, by means of an external charging device, a secondary cell in equipment capable of housing a primary cell and a secondary cell as built-in cells, the circuit comprising: a first terminal voltage detection circuit which detects a terminal voltage of the secondary cell of the built-in cells and a terminal voltage of the primary cell of the same which detects the built-in cell as a secondary cell even when a predetermined terminal voltage is detected from only the terminal voltage of the secondary cell, and which detects a short circuit when the predetermined terminal voltage has been detected in the terminal voltage of the secondary cell and the terminal voltage of the primary cell; a second terminal voltage detection circuit for detecting that the built-in cell is an overdischarged secondary cell when the first terminal voltage detection circuit has not detected the predetermined terminal voltage and when a voltage drop has been detected by application of a predetermined voltage to the terminal of the secondary cell of the built-in cell; and a control circuit which allows the external charging device to charge the built-in cell when the first terminal voltage detection circuit and the second terminal voltage detection circuit have detected that the built-in cell is a secondary cell and when the short circuit is not detected.