Patent ID: 9192004
Filing Date: 2015-11-17
Classification: H05B

Abstract:
1. A light-emitting diode (LED) driver, comprising: a) a silicon-controller rectifier (SCR) coupled to an AC power supply, and configured to generate a DC voltage through a first rectifier circuit; b) a first stage power converter circuit having an isolated topology with a power factor correction function, wherein said first stage power converter circuit is configured to convert said DC voltage to a first output voltage; c) said first stage power converter circuit comprising a transformer having a primary winding coupled to said DC voltage, and a secondary winding coupled to said first output voltage through a second rectifier circuit; d) a second stage power converter circuit having a non-isolated topology, wherein said second stage power converter circuit is configured to convert said first output voltage to an output current configured to drive an LED load based on a conduction angle of said SCR; e) a dimming circuit coupled to said first stage power converter circuit, and configured to output a dimming signal that represents said SCR conduction angle, wherein said dimming circuit comprises a square wave signal generating circuit coupled to said secondary winding of said transformer, and is configured to output a square-wave signal as said dimming signal; and f) a first control circuit configured to receive an LED current signal and said dimming signal, and to control a second stage power switch to convert said first output voltage to said output current to drive said LED load.