Patent ID: 8432108
Filing Date: 2013-04-30
Classification: H02M,H05B,Y02B

Abstract:
1. A solid state lighting driver circuit comprising: an EMI filter configured and arranged to receive an AC input from an AC power supply; a rectifier connecting the EMI filter, the rectifier being configured and arranged to receive AC power from the EMI filter and produce a rectified current; a power factor correction (PFC) stage including a boost circuit connected to the rectifier, the boost circuit being configured and arranged to receive the rectified current and to produce a power factor corrected output with a higher voltage than the AC input of the AC power supply; a Buck regulator configured and arranged to receive power from the PFC stage and regulate power for supply to a plurality of LEDs; and a controller configured and arranged to control the Buck regulator and PFC stage for hysteretic PFC start-up, wherein the controller is configured and arranged to (i) with the output current of the PFC stage at zero, and with the Buck regulator in an off condition, cause the PFC stage to turn on and begin to charge a boost capacitor, (ii) when a desired high fixed voltage across the boost capacitor is reached, turn the Buck regulator on at a low current value and turn off the PFC stage allowing the boost capacitor to discharge to a lower fixed voltage as it supplies current to the plurality of LEDs, (iii) adjust a ramp-up voltage time, between the lower fixed voltage and the high fixed voltage, to equal a ramp-down voltage time between the high fixed voltage and the lower fixed voltage, and (iv) turn the PFC stage back on.