Patent ID: 7592755

Claim:
A light source driving circuit, for driving a first light-emitting element, comprising: a power supply circuit, having an output terminal and a feedback terminal, wherein the output terminal is connected to at least one of the terminal of the first light-emitting element to supply a voltage to the first light-emitting element, and the power supply circuit determines a value of the voltage according to a feedback signal received by the feedback terminal; a first dimming circuit, having a first terminal, a second terminal, and a pulse width signal input terminal, wherein the first terminal is connected to another terminal of the first light-emitting element, and the second terminal is connected to a common potential; and a feedback circuit, connected between the pulse width signal input terminal of the first dimming circuit and the feedback terminal of the power supply circuit, for receiving and transmitting a pulse width signal to the pulse width signal input terminal of the first dimming circuit, such that the first dimming circuit determines an ON/OFF state between the first terminal and the second terminal according to a logic state of the pulse width signal, and the feedback circuit turns off the power supply circuit to stop supplying the voltage and delays the first dimming circuit to turn off regarding a specific logic state of the pulse width signal.