Patent ID: 8018701

Claim:
A backlight control circuit, comprising: a load comprising a plurality of lamps, each lamp including a first terminal; an inverter circuit configured to drive the load; a pulse width modulation integrated circuit (PWM IC) connected to the load via the inverter circuit, and comprising a protecting output; a protecting circuit connected to the protecting output of the PWM IC, the protecting circuit having a reference voltage and comprising a charging branch and a comparison circuit, the comparison circuit configured for cutting off the charging branch; and a first feedback circuit connected to the first terminals of the lamps, the PWM IC, and the protecting circuit, the first feedback circuit capable of detecting voltage from the first terminals of the lamps; wherein the first feedback circuit is capable of outputting a voltage to the protecting circuit, the output voltage corresponding to the voltage detected from the first terminals, and the protecting circuit is configured to control the PWM IC to stop outputting a backlight adjusting signal to the inverter circuit such that the inverter circuit stops driving the load when the output voltage is higher than the reference voltage of the protecting circuit; wherein the comparison circuit comprises a comparator including a positive input, a negative input, and an output end, a first resistor, a second resistor, and a reference voltage input terminal, the reference voltage input terminal is grounded via the first resistor and the second resistor in sequence, the positive input of the comparator is connected to a node between the first resistor and the second resistor, the negative input of the comparator is connected to the first feedback circuit, the charging branch comprises a current-limiting resistor, a diode, and a charging capacitor, and the current-limiting resistor is grounded via the diode and the charging capacitor in sequence, a positive terminal of the diode connected to the current-limiting resistor and a negative terminal of the diode connected to the comparison circuit and the charging capacitor.