Patent ID: 8975831
Filing Date: 2015-03-10
Classification: H05B,Y02B

Abstract:
1. A method for controlling a regulator for dimming of a light emitting diode (LED) load comprising: providing a first dimming signal having a first frequency and a selectable duty cycle for controlling a ratio of LED ON-times versus LED OFF times, the first dimming signal generating an ON-pulse for each ON/OFF cycle; providing a second dimming signal, delayed from the first dimming signal, the second dimming signal having substantially the same first frequency and duty cycle of the first dimming signal, the second dimming signal controlling the LED ON-time and the LED OFF-times; controlling a regulator by the second dimming signal to supply current to the LED load during the LED ON-time, and to supply no current to the LED load during the OFF-time, the regulator having an inductor; detecting an inductor current during a steady-state condition of the regulator during the ON-time to generate a first value corresponding to the inductor current; storing the first value during the OFF-time; pre-charging the inductor to a target current level related to the stored first value, prior to a next ON-time of the LED load, the pre-charging being initiated by the ON-pulse in the first dimming signal; after the inductor has been pre-charged to the target current level, stopping pre-charging the inductor and controlling the second dimming signal to apply an ON-time pulse to the regulator to supply current to the LED load during the LED ON-time; and maintaining a control signal in a feedback loop of the regulator substantially constant during the OFF-time, wherein the inductor is pre-charged with a current approximately equal to the inductor current during the steady-state condition of the regulator so that the current supplied to the LED load at the beginning of an ON-time is approximately equal to the current supplied to the LED load at the end of the previous ON-time.