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Short circuit detection for lighting circuits

  • US 9,084,330 B2
  • Filed: 07/16/2013
  • Issued: 07/14/2015
  • Est. Priority Date: 11/30/2012
  • Status: Active Grant
First Claim
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1. A fault-tolerant controller for a lighting system comprising a plurality of LED circuits and a controllable power source providing a drive voltage to power the plurality of LED circuits, the fault-tolerant controller comprising:

  • a control unit configured to cause regulation of the drive voltage based on a determination of a plurality of feedback voltages, one feedback voltage for each of the plurality of LED circuits; and

    a fault condition detecting means configured to identify one or more fault conditions from the plurality of feedback voltages, wherein at least one of the LED circuits is determined as a fault circuit having a fault condition for which the respective feedback voltage is below a first fault circuit condition threshold, wherein the fault condition detecting means is further configured, in response to a detected fault condition, to apply a test voltage to a cathode of the fault-circuit and, if the feedback voltage of the fault circuit remains below a second fault circuit condition threshold, the fault circuit is determined to have a short circuit condition, wherein the fault condition detecting means comprises a plurality of pull-up circuits, each pull-up circuit provided between ground voltage and a cathode for each LED circuit, wherein each pull-up circuit comprises a voltage source and a switch, the fault condition detecting means being configured to cause closing of the switch associated with the fault circuit upon detecting a fault condition to apply the test voltage to the cathode of the fault circuit.

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