Patent ID: 9018855
Filing Date: 2015-04-28
Classification: H02M,H05B

Abstract:
1. A controlling circuit for a light-emitting diode (LED) driver having a transformer, said controlling circuit comprising: a) a sampling circuit configured to generate a sampling signal that indicates an output current signal of said LED driver at a primary side of said transformer; b) an on time sensing circuit configured to sense an on time of an output diode arranged at a secondary side of said transformer; c) a regulating signal generator configured to generate a regulating signal based on said sampling signal, a voltage reference that is directly proportional to an expected output current of said LED driver, and said on time of said output diode, wherein said regulating signal generator comprises an operational amplifier; and d) a pulse-width modulation (PWM) controller configured to generate a controlling signal to control operation of a switching device of said LED driver based on said regulating signal, and wherein an on time of said switching device is controlled by said regulating signal.