Patent ID: 7531971

Claim:
A backlight unit in a normal mode or a standby mode, comprising: a boost circuit coupled to a voltage source and controlled by a pulse width modulation (PWM) signal and a switch signal; and a backlight element driven by the boost circuit; wherein, in the normal mode, the boost circuit is supplied by the voltage source according to the PWM signal and the switch signal to drive the backlight element to emit light; wherein, in the standby mode, according to the PWM signal and the switch signal, the voltage source stops supplying the boost circuit, and the backlight element stops emitting light; and wherein the boost circuit comprises: a first switch having a control terminal receiving the switch signal an input terminal coupled to the voltage source, and an output terminal coupled to a first node; an inductor coupled between the first node and a second node; a second switch having a control terminal receiving the PWM signal, an input terminal coupled to the second node, and an output terminal coupled to a ground; a diode having a first terminal coupled to the second node, and a second terminal coupled to a first terminal of the backlight element at a third node; and a capacitor coupled between the third node and the ground.