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Discrete Hot Swap and Overcurrent-Limiting Circuit

  • US 20090027818A1
  • Filed: 07/27/2007
  • Published: 01/29/2009
  • Est. Priority Date: 07/27/2007
  • Status: Active Grant
First Claim
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1. A system comprising:

  • a live backplane adapted to provide a voltage to one or more circuit cards connected thereto; and

    at least one protected circuit card adapted to couple to said live backplane, said protected circuit card including a discrete protection circuit adapted to limit the current provided to said protected circuit card when said protected circuit card is coupled to said backplane, said discrete protection circuit comprising;

    a first capacitor adapted to receive an input and accumulate a charge accordingly;

    a sense resistor adapted to sense a load current and have a voltage proportional to said load current so that an overcurrent condition can be detected by sensing the voltage across said sense resistor.a switch adapted to control a load current delivered to an output port;

    a discrete SCR adapted to latch when an overcurrent condition is detected, thereby preventing the flow of said load current to said output port; and

    a series of two resistors coupled between said first capacitor and ground, the series of resistors adapted to set a charge time for said first capacitor, said charge time controlling the retry delay subsequent to the detection of an overcurrent condition.

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