Charge and discharge control circuit and apparatus for secondary battery

  • US 6,194,871 B1
  • Filed: 04/24/2000
  • Issued: 02/27/2001
  • Est. Priority Date: 12/03/1999
  • Status: Expired due to Term
First Claim
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1. A charge and discharge control circuit for an external secondary battery, the charge and discharge control circuit making an external charge control switch nonconductive based on that an overcharge state of the external secondary battery is detected and interrupting a charge operation of the external secondary battery, the charge and discharge control circuit comprising:

  • a charge control element for making the charge control switch conductive when a first voltage not less than a predetermined voltage is applied to a detection terminal for detecting whether a charger is connected thereto or not, thereby making the charge operation of the secondary battery possible, and for making the charge control switch nonconductive when a second voltage not more than the predetermined voltage is applied to the detection terminal, thereby making the charge operation of the secondary battery impossible.

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