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Deep dimming of an LED-based illumination device

  • US 9,788,379 B2
  • Filed: 03/26/2015
  • Issued: 10/10/2017
  • Est. Priority Date: 03/28/2014
  • Status: Active Grant
First Claim
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1. A method of controlling an average current supplied to an LED based illumination device, comprising:

  • receiving an indication of a desired average current level that differs from a first average current level supplied to a light emitting diode (LED) of the LED based illumination device;

    generating a digital control signal with a comparator circuit for periodically switching a current supplied to the LED of the LED based illumination device from a high state to a low state over a switching period while generating an analog control signal with a digital to analog conversion circuit for adjusting a value of the current supplied to the LED during the high state, adjusting a duration of the switching period and adjusting a ratio of a time in the high state to a time in the low state by adjusting with the comparator circuit both the time in the high state and the time in the low state, as the average current supplied to the LED of the LED based illumination device transitions from the first average current level to the desired average current level; and

    supplying the current to the LED of the LED based illumination device based on the analog control signal and the digital control signal.

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