Patent ID: 8471483

Claim:
A multi-channel LED driving system, comprising: a power adapter; a rectifying and filtering unit electrically connected to the power adapter; a plurality of LED strings, composed of multiple serial light emitting diodes, electrically connected to the rectifying and filtering unit in parallel, respectively; a plurality of linear regulators respectively electrically connected to the LED strings, wherein each linear regulator comprises a switch diode and a MOSFET; a constant current and constant voltage (CC/CV) controller electrically connected to the linear regulators; an optically coupled isolator had a light-emitting side and a light-detecting side, the light-emitting side electrically connected to the CC/CV controller, thus receiving a current provide by conduction of the CC/CV controller and isolated transmitting to the light-detecting side; a pulse width modulation (PWM) controller electrically connected to the power adapter and the optically coupled isolator for receiving a detecting signal transmitted from the optically coupled isolator and then controlling the power adapter according to the detecting signal; and a protective unit electrically connected to the CC/CV controller and the linear regulators, the protective unit comprising: a voltage regulator; a first operation amplifier having an inverting input terminal and the inverting input terminal electrically connected to the voltage regulator; a plurality of protective resistors electrically connected to a non-inverting input terminal of the first operation amplifier and the rectifying and filtering unit; wherein, the first operation amplifier compares the DC voltage source outputted from the rectifying and filtering unit and the voltage of the voltage regulator to provide over-voltage protection and LED open circuit protection; whereby the CC/CV controller detects the conducting currents flowing through the LED strings and DC voltage sources outputted from the rectifying and filtering unit to provides voltage compensation of the power adaptor, the linear regulators modulate difference between the conducting currents of the LED strings to achieve current sharing control.