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ADAPTIVE ALGORITHM FOR CAMERA FLASH LED POWER CONTROL VS. BATTERY IMPEDANCE, STATE OF DISCHARGE (SOD), AGING, TEMPERATURE EFFECTS

  • US 20090121644A1
  • Filed: 10/29/2008
  • Published: 05/14/2009
  • Est. Priority Date: 11/14/2007
  • Status: Active Grant
First Claim
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1. A method for driving a light-emitting semiconductor, the method comprising:

  • converting a supply voltage into a secondary output voltage for supplying the light-emitting semiconductor with an output voltage;

    sensing a level for the supply voltage at the beginning of a high current phase of the light-emitting semiconductor;

    determining a threshold voltage level for the supply voltage level based on the sensed level;

    starting the high current phase with the light-emitting semiconductor;

    continuously comparing the sensed level with the threshold voltage level; and

    controlling an output current through the light-emitting semiconductor such that the sensed level does not drop below the threshold voltage level.

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