Patent ID: 8456108
Filing Date: 2013-06-04
Classification: H05B

Abstract:
1. An LED lighting apparatus comprising: a triac dimmer configured to phase-control an AC input voltage at a given phase ratio and output a phase-controlled AC voltage; a series circuit connected to the triac dimmer and including a primary winding of a switching transformer and a switching element, the switching transformer having a plurality of windings; a controller configured to control ON/OFF of the switching element; a rectifying-smoothing circuit having a first rectifying element and a first smoothing element and configured to rectify and smooth a voltage generated by a secondary winding of the switching transformer; LEDs connected to an output of the rectifying-smoothing circuit; a current detector configured to detect a current passing through the LEDs and output a current detection signal; a voltage detector configured to output a voltage detection signal proportional to a phase ratio of the AC input voltage, the voltage detection signal being based on a winding voltage generating at the secondary winding of the switching transformer or n-th order winding thereof, and the n-th order winding being electromagnetically coupled with the secondary winding wherein n≧3; and an amplifier configured to amplify a voltage associating with the current detection signal and voltage detection signal and output the amplified voltage to the controller.