| 摘要 |
<p>A backlight driving circuit comprises a constant-current driving chip (20), a power supply module (10), and an LED light bar (30) which is coupled to the power supply module (10). The constant-current driving chip (20) comprises a control module for controlling the switching frequency of the power supply module (10), and a sensing module (23) regulating a duty cycle of an effective current flowing through the LED light bar (30). The control module (21) is provided with a frequency pin (22) used for setting the switching frequency of the power supply module (10). The sensing module (23) is coupled to an external PWM dimming signal. The backlight driving circuit also comprises a detecting module (40) for acquiring a duty cycle of the PWM dimming signal, and a monitoring module (50) coupled to the detecting module (40). When the duty cycle of the PWM dimming signal is less than a preset threshold, the monitoring module (50) outputs a signal for reducing the frequency to the frequency pin (22).</p> |
