Patent ID: 8847510
Filing Date: 2014-09-30
Classification: H05B,Y02B

Abstract:
1. An LED AC driving circuit capable of adjusting operating voltage, comprising: a rectifying unit receiving and converting AC power to pulsed DC power and output the pulsed DC power through an output; an LED unit connected to the output of the rectifying unit to form a power loop and comprising multiple LEDs; a voltage-controlled transistor for adjusting a loop current of the power loop, wherein the voltage-controlled transistor connects to the power loop in series and has a control terminal, a first pole and a second pole; a current detecting unit connecting to the power loop in series and converting the loop current to a voltage signal; a low frequency filter connecting to the current detecting unit and outputting a voltage based on the voltage signal; a resistance adjusting unit connecting to the voltage-controlled transistor and being capable of adjusting a resistance across the voltage-controlled transistor; and a current regulating unit having wherein the current regulating unit compares the voltage from the low frequency filter with the reference voltage to produce a control signal applied to the control terminal of the voltage-controlled transistor for stabilizing the loop current, and detects operating power of the voltage-controlled transistor for controlling the resistance adjusting unit to change the resistance across the voltage-controlled transistor.