Patent ID: 9183788
Filing Date: 2015-11-10
Classification: G09G,H05B

Abstract:
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 module 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, wherein a photoresistor is connected in series between the frequency pin and a ground terminal of the backlight driving circuit; the photoresistor is arranged on a position directly irradiated by the LED lightbar.