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Computer card having power switching capability

  • US 5,451,933 A
  • Filed: 09/06/1994
  • Issued: 09/19/1995
  • Est. Priority Date: 10/19/1992
  • Status: Expired due to Term
First Claim
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1. A battery powered electronic device for coupling to a host device for performing operational functions both when coupled to and disconnected from the host device, the electronic device comprising:

  • a battery for normally powering the operational functions performed by the battery powered electronic device;

    an interface comprising data transmission means for transmitting data and power receiving means for receiving power from the host device; and

    electronic circuitry for performing the operational functions, including receiving information and generating the data, comprising;

    interface monitoring means coupled to the interface for determining an interface status as being active or inactive; and

    power switching means coupled to the interface monitoring means for coupling the electronic circuitry to the battery in response to the interface monitoring means determining that the interface is inactive and for coupling the electronic circuitry to the power receiving means in response to the interface monitoring means determining that the interface is active, wherein the power for performing the operational functions is provided by the battery when the interface is inactive, wherein the power for performing the operational functions is provided by the host device when the interface is active, and wherein the power switching means operates irrespective of an external supply voltage level of the power supplied by the host device.

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