A liquid crystal display (LCD) device includes a liquid crystal display (LCD) panel and a backlight unit. Generally, a typical backlight unit uses a light emitting diode (LED) as a backlight source, thus, an LED backlight driving circuit is used to adjust brightness of an LED light bar. The LED backlight driving circuit includes a driving chip. Because temperature of the backlight unit can be excessive, a thermal protection circuit is arranged at an external of the driving chip to avoid damage to the driving chip. As shown in FIG. 1, the thermal protection circuit includes a comparator P, a non-inverting input end of the comparator P receives a constant reference voltage, and an inverting input end of the comparator P is connected to a collector of a BJT Q. Voltage between the collector of the BJT and a gate of the BJT reduces at high temperatures, and when the voltage is less than the constant reference voltage, the comparator P outputs an over-temperature protection signal OTP to the driving chip 10 to turn off the LED light bar, which allows for thermal protection of the driving chip. A typical thermal protection circuit is not flexible, and has small application range.
USPTO Backgrounds
USPTO Backgrounds