BACKLIGHT DRIVING CIRCUIT, LCD DEVICE, AND METHOD FOR DRIVING THE BACKLIGHT DRIVING CIRCUIT

摘要

A backlight driving circuit includes a constant current driving chip, a power module, and a light emitting diode (LED) lightbar coupled with the power module. The constant current driving chip includes a control module that controls switching frequency of the power module, and an adjusting module that adjusts duty cycle of effective current flowing through the LED lightbar. The control module includes a frequency pin used to set the switching frequency of the power module. An external pulse-width modulation (PWM) dimming signal is sent to the adjusting module of the constant current driving chip. The backlight driving circuit further includes a detection module that detects duty cycle of the PWM dimming signal, and a monitor module coupled with the detection module of the backlight driving circuit.

主权项

1. A backlight driving circuit, comprising:
a constant current driving chip; a power module; a light emitting diode (LED) lightbar coupled with the power module; a detection module that detects duty cycle of a pulse-width modulation (PWM) dimming signal; and a monitor coupled with the detection module; wherein the constant current driving chip comprises a control module that controls switching frequency of the power module, and an adjusting module that adjusts a duty cycle of an effective current flowing through the LED lightbar; wherein the control module comprises a frequency pin used to set the switching frequency of the power module; an external PWM dimming signal is sent to the adjusting module of the constant current driving chip; when the duty cycle of the PWM dimming signal is less than a preset threshold, the monitor module outputs a signal to the frequency pin to reduce the switching frequency of the power module.