LED backlight drive circuit and liquid crystal display

Abstract

The embodiment of the invention discloses an LED backlight drive circuit which comprises a power supply, an LED string, a protection circuit and a drive chip, wherein the LED string comprises a plurality of LED lamps; a positive end of the LED string is electrically connected with a power supply; one end of the protection circuit is electrically connected with a negative end of the LED string; a first pin of the drive chip is electrically connected with the other end of the protection circuit; when the LED string normally works, the protection circuit is conducted; when two ends of LED lamps in the LED sting are shorted, the protection circuit is automatically cut off to be used for protecting the drive chip. The embodiment of the invention further discloses the liquid crystal display. By adopting the LED backlight drive circuit and the liquid crystal display, the damage to the pin of the drive chip can be reduced.

Description

technical field [0001] The invention belongs to the technical field of liquid crystal display, and in particular relates to an LED backlight driving circuit and a liquid crystal display. Background technique [0002] With the continuous progress of display technology, the backlight technology of liquid crystal display has been continuously developed. Traditional LCD backlights use cold cathode fluorescent lamps (CCFL). However, due to the shortcomings of CCFL backlight such as poor color reproduction ability, low luminous efficiency, high discharge voltage, poor discharge characteristics at low temperature, and long time for heating to reach a stable gray level, LED (Light Emitting Diode, Chinese name: Light-emitting diode) backlight technology. [0003] figure 1 It is an existing LED backlight driving circuit for liquid crystal displays. like figure 1 As shown, the LED backlight driving circuit includes a power supply, an LED string and a driver chip. Specifically, the...

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Problems solved by technology

[0004] In the process of using the above-mentioned LED backlight driving circuit, the inventor of the present invention found that in the process of using the liquid crystal display, sometimes one end of the LED light (such as the + terminal) and the other end of the LED light (such as the - terminal) are short-circuited ( figure 1 Indicates that the two ends of the last LED are short-circuited), resulting in an increase in the voltage at the pin where the driver chip is electrically connected to the LED string, and this pin is a low-voltage pin, once the voltage at the pin is higher than the withstand voltage of the pin value, the pins of the driver chip will be broken down, resulting in damage to the driver chip, and even sparks in severe cases, which will bring hidden dangers to system safety

[0005] The existing technology provides two solutions, one of which is to build a high-voltage-resistant transistor at the pin of the driver chip, but this kind of solution is complicated in manufacturing process, which will increase the manufacturing cost of the driver chip; The pins of the chip have built-in low-voltage-resistant transistors. Although the manufacturing cost of this solution is low, when the voltage is higher than the withstand voltage of the transistors, the pins of the driver chip will be broken down, resulting in damage to the pins of the driver chip. ; so neither solution is ideal

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