Patent ID: 8773027
Filing Date: 2014-07-08
Classification: H05B

Abstract:
1. A current-shunting alternating current (AC) light-emitting diode (LED) driving circuit comprising: a rectification unit having: an LED unit having multiple LEDs and connected to the output terminal of the rectification unit to constitute a power loop; a voltage-controlled transistor serially connected to the power loop and having a control terminal for adjusting a loop current flowing through the power loop; a shunt resistor parallelly connected to the voltage-controlled transistor and having a resistance value in a range with a lower bound not less than a value of a maximum operating voltage of the voltage-controlled transistor divided by a rated current defined as the loop current when the voltage-controlled transistor is cut off and an upper bound not greater than a value of dividing the maximum operating voltage by a current difference value obtained by a difference between the rated current and a value of dividing a peak power withstood by the voltage-controlled transistor by the maximum operating voltage; a current detection unit serially connected to the power loop and converting the loop current of the power loop into a corresponding voltage signal; a low-pass filter connected to the current detection unit and outputting an average voltage according to the voltage signal converted by the current detection unit; and a steady current control unit having: the steady current control unit comparing a value of the average voltage outputted by the low-pass filter with a value of the received reference voltage, and outputting a control signal to the control terminal of the voltage-controlled transistor according to the comparison result so as to stabilize the loop current of the power loop.