| 摘要 |
An LED(Light Emitting Diode) driving circuit for a backlight having a constant current is provided to stabilize an LED driving current by controlling a driving current of the LED to a constant current. A switch(SW4) is connected between a DC(Direct Current) voltage terminal and a ground(GND), and switches the DC voltage (Vin) according to a switching pulse(SP). A rectification diode(D4) is connected between a connection node between the DC voltage terminal and the switch, and one end of the LED array(T11), and rectifies a driving current supplied according to a switching operation of the switch. A smoothing capacitor(C4) is connected to one end of a cathode of the rectification diode, and is connected to the other end of the ground. A voltage detection resistance(Rd) is connected between the other end(T12) of the LED array connected to the ground and the other end of the smoothing capacitor, and detects a current flowing to the ground as a voltage. A PWM(Pulse Width Modulation) controller controls ON/OFF of the switch with the switching pulse having a duty rate determined by a preset internal reference voltage and a detection voltage(Vd) detected by the voltage detection resistance.
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