Patent ID: 8384304
Filing Date: 2013-02-26
Classification: H05B

Abstract:
1. An LED driver controller, comprising: an auto-gain control unit, having a first input end configured to receive an input voltage signal which is derived from a line voltage, and an output end for providing a normalized signal, wherein said normalized signal is generated by detecting the amplitude of said input voltage signal and dividing said input voltage signal with said amplitude; a first comparator, used to perform voltage comparison on said normalized signal and a current sensing signal to generate a turn-off signal, wherein said turn-off signal will change state from inactive to active when said current sensing signal reaches said normalized signal; a driving circuit, having a second input end, a third input end, and an output end, said second input end configured to receive a first turn-on signal, said third input end being configured to receive said turn-off signal, and said output end being used for providing a gating signal, wherein said gating signal is active when said first turn-on signal is active, and inactive when said turn-off signal is active; a boundary detection unit, having a fourth input end which receives said input voltage signal, and an output end which generates a second turn-on signal which is generated by comparing said input voltage signal and a first threshold signal, wherein said first threshold signal is proportionate to a sampled voltage of said input voltage signal at a rising edge of said turn-off signal, and said second turn-on signal will change state from inactive to active when said input voltage signal falls below said first threshold signal; a turn-on signal generator, used to generate a third turn-on signal, which is a signal selected from the group consisting of a constant-frequency signal and a constant-off-time signal; and an OR gate, having a fifth input end configured to receive said second turn-on signal, a sixth input end configured to receive said third turn-on signal, and an output end for outputting said third turn-on signal.