Patent ID: 8547026

Claim:
An LED (Light-Emitting Diode) backlight driving circuit, the LED backlight driving circuit comprising: a number of LED light strings connected in parallel; a switch module, which comprises the same number of switches as the LED light strings, the switches being arranged to respectively correspond to and connect in series with the LED light strings; a power module, which is electrically connected to the LED light strings; and a switching control module, which controls currents of the LED light strings; wherein the switching control module comprises: a driving unit, which is connected to the switches; a current detection unit, which is connected to the switches to detect the currents of the switches; an ON time detection unit, which is connected to the driving unit to detect an ON time of each of the switches; a reference unit, the reference unit supplying a reference value; multipliers of the same number as the LED light strings, each of the multipliers having two input terminals respectively the ON time detection unit and the current detection unit to receive a ON time value of a corresponding one of the switches and a voltage signal indicating the current of the switch; comparison units of the same number as the LED light strings, each of the comparison units having two input terminals respectively connected to the reference unit and an output terminal of a corresponding one of the multipliers, each of the comparison units having an output terminal connected to the driving unit, the driving unit controlling the ON time of the switch corresponding to the comparison unit according to an output result of the comparison unit; and current detection resistors, the current detection resistors being of a number corresponding to the number of the switches and being respectively connected in series to the switches; wherein the reference unit comprises: a constant current source that supplies a constant electrical current, an resistor connected to an input terminal of the constant current source, a period unit that supplies a period value for the driving unit to drive the switches, and a multiplication unit, an output terminal of the constant current source and an output terminal of the period unit being respectively connected to two input terminals of the multiplication unit, the multiplication unit having an output terminal serving as an output terminal of the reference unit and connected to each of the comparison units.