LED backlight driving circuit having divider units and method for driving the LED backlight driving circuit

摘要

A light emitting diode (LED) backlight driving circuit includes a power supply, an LED light bar coupled to the power supply, a constant current driving chip that drives the LED light bar to light, and a comparing unit. The constant current driving chip includes an under-voltage protection pin that receives an under-voltage protection signal. An overvoltage collecting unit of the LED backlight driving circuit and an under-voltage collecting unit of the LED backlight driving circuit are coupled to an input end of the power supply, and an output voltage of the under-voltage collecting unit is directly input to the under-voltage protection pin. A reference voltage is input to a first input end of the comparing unit, and a second input end of the comparing unit is coupled to the overvoltage collecting unit. When an output voltage of the overvoltage collecting unit exceeds the reference voltage, the comparing unit sends the under-voltage protection signal to the under-voltage protection pin.

主权项

1. A light emitting diode (LED) backlight driving circuit, comprising:
a power supply; an LED light bar coupled to the power supply; a constant current driving chip that drives the LED light bar to light; and a comparing unit; wherein the constant current driving chip comprises an under-voltage protection pin that receives an under-voltage protection signal, and an overvoltage collecting unit of the LED backlight driving circuit and an under-voltage collecting unit of the LED backlight driving circuit are coupled to an input end of the power supply; an output voltage of the under-voltage collecting unit is directly input to the under-voltage protection pin; a reference voltage is input to a first input end of the comparing unit, and a second input end of the comparing unit is coupled to the overvoltage collecting unit; when an output voltage of the overvoltage collecting unit exceeds the reference voltage, the comparing unit sends the under-voltage protection signal to the under-voltage protection pin, wherein the under-voltage protection signal is a low level signal; the overvoltage collecting unit comprises a first divider unit and a second divider unit that are connected in series between the input end of the power supply and a ground terminal; the first input end of the comparing unit is a non-inverting input end, and the second input end of the comparing unit is an inverting input end; when voltage of the second divider unit exceeds the reference voltage, the comparing unit sends the low level signal to the under-voltage protection pin.