Patent ID: 9271366
Filing Date: 2016-02-23
CPC Classification: H05B,Y02B

Claim Text:
1. A dimmable light-emitting diode (LED) driver, comprising: a) a silicon-controlled rectifier (SCR), an electronic transformer, and a rectifier bridge configured to convert an AC voltage to a DC voltage signal; b) a power stage circuitry configured to receive said DC voltage signal, and to output a constant current to drive an LED load, wherein said power stage circuitry comprises first and second power stage circuits, wherein said first power stage circuit is configured to receive said DC voltage signal, and to generate a first output voltage to said second power stage; c) an input current control circuit configured to receive an input current of said first power stage circuit and said first output voltage, and to generate a first control signal to control said input current as a pseudo square waveform signal, wherein a high frequency saw-tooth waveform is formed from upper portions of said pseudo square waveform signal during an on time of said SCR; d) wherein a peak value of said saw-tooth waveform is configured to satisfy a minimum load current requirement of said electronic transformer, and lower portions of said pseudo square waveform signal are maintained as substantially zero; and e) said second power stage circuit being configured to generate a substantially constant output current to drive said LED load in accordance with said input current.