| 摘要 |
<p>An LED backlight driving circuit comprises: a first power supply module (2), an inductor (L), a rectifier diode (D), an MOS tube (Q), an electrolytic capacitor (C), an LED lamp string (4), a voltage dividing module (6), a voltage comparator (7), a second power supply module (8) and an LED constant current driving chip (9). The LED backlight driving circuit adds the voltage comparator (7) in an external line of the LED constant current driving chip (9) for detecting output voltage of the driving circuit. In a high-voltage situation, a low level output by the voltage comparator (7) is used for forcibly pulling down a PWM dimming signal or an ENA enabling signal on the LED constant current driving chip (9), implementing a function of over-voltage protection. Meanwhile, the LED backlight driving circuit removes an existing output over-voltage protection function module from the LED constant current driving chip (9), enabling a size of the LED constant current driving chip (9) to be smaller, reducing a production cost, better protecting the LED constant current driving chip (9) and avoiding a risk that the LED constant current driving chip is damaged by high voltage.</p> |
