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Electronic circuit with power drain control

  • US 4,908,523 A
  • Filed: 04/04/1988
  • Issued: 03/13/1990
  • Est. Priority Date: 04/04/1988
  • Status: Expired due to Term
First Claim
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1. A power switching circuit for selectively coupling an output terminal to a first or a second battery, the circuit comprising:

  • a first input terminal for connection to the first battery;

    a second input terminal for connection to the second battery;

    an output terminal;

    first switching means responsive to the voltage of the first battery for selectively switching the output terminal from the first to the second input terminal in response to the voltage of the first battery falling to a first predetermined level, said first switching means including a comparator coupled to compare the voltage of a primary one of said first or second batteries at the first input terminal with a first reference voltage;

    second switching means controllable by said first switching means;

    a second output terminal coupled to the first input terminal through said second switching means, said second switching means for isolating the second output terminal from the first battery in response to the voltage of the first battery falling to a second predetermined level.

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