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Battery charge indicator for implantable pacemakers and defibrillators

  • US 7,215,999 B1
  • Filed: 08/06/2003
  • Issued: 05/08/2007
  • Est. Priority Date: 08/06/2003
  • Status: Active Grant
First Claim
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1. A method for tracking battery usage in an implantable cardiac device, the method comprising:

  • routing current drawn from a battery through a current one of a plurality of selectable circuit configurations, each configuration corresponding to one of a plurality of ranges of current values;

    measuring the voltage drop across the current circuit configuration;

    generating a first signal based on the voltage drop, the first signal indicative of the load current being drawn from the battery;

    for each first signal, generating a corresponding second signal indicative of the current range within which the load current falls;

    switching to another of the plurality of selectable circuit configurations if the load current falls outside the range of the current circuit configuration;

    repeating the measuring, generating and switching over time; and

    determining usage of the battery by accumulating the load current over time as a function of corresponding first and second signals.

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