Patent ID: 8446106

Claim:
A light emitting diode (LED) driving system, to drive a plurality of LED strings, wherein the LED driving system comprises: a converter, to convert an external power signal into a direct current power signal able to drive the LED strings; a controller, to control the converter to output the direct current power signal; a plurality of current limitation circuits, correspondingly connected to the LED strings, wherein each of the current limitation circuits comprises: a first switch, comprising a control pole, a first pole, and a second pole, the control pole connected to a reference voltage, the first pole connected to a corresponding LED string, and the second pole grounded via a first resistor; and a second switch, comprising a control pole, a first pole and a second pole, the control pole of the second switch connected to the second pole of the first switch via a second resistor, the first pole of the second switch connected to the control pole of the first switch, and the second pole of the second switch being grounded; and a plurality of over-voltage protection circuits correspondingly connected to the LED strings, wherein each of the over-voltage protection circuits comprises: a zener diode with a cathode connected to a corresponding LED string together with the first pole of the first switch; a third switch, comprising a control pole, a first pole and a second pole, the control pole of the third switch connected to an anode of the zener diode by way of a third resistor, the first pole of the third switch connected to the control pole of the first switch, and the second pole of the third switch being grounded; and a first capacitor, connected between the control pole of the third switch and the ground; wherein the control pole of the first switch, the first pole of the second switch and the first pole of the third switch all connect to the reference voltage via a fourth resistor.