Backlight driving circuit and liquid crystal display

Abstract

The invention discloses a backlight driving circuit. The backlight driving circuit comprises a voltage stabilizing circuit, a boost circuit and a control circuit. The voltage stabilizing circuit receives input voltage, filters the input voltage and outputs voltage stabilizing direct current. The boost circuit is connected with the voltage stabilizing circuit, receives the voltage stabilizing direct current, boosts and outputs the voltage stabilizing direct current to a light emitting diode (LED) light bar. The control circuit is connected with the boost circuit and is used for supplying a pulse width modulation (PWM) square wave and controlling the boost circuit to supply power for the LED light bar. The boost circuit comprises a metal oxide semiconductor (MOS) pipe or an audion. At least three resistors with near or same value of resistance are in parallel connection between a source electrode of the MOS pipe or a collector of the audion and the ground. Accordingly, the invention further provides a liquid crystal display adopting the backlight driving circuit. The backlight driving circuit and the liquid crystal display can improve the accuracy of the current output to the LED light bar.

Description

technical field [0001] The present invention relates to the field of liquid crystal displays, in particular to a backlight drive circuit and a liquid crystal display. Background technique [0002] In the prior art light emitting diode (Light Emitting Diode, LED) backlight driving circuit of a liquid crystal display, a Boost circuit (the boost converter or step-up converter, switching DC boost circuit) is usually used to supply power to the LED. [0003] Such as figure 1 As shown, the inductor L1, diode D10, resistor R10, capacitor C1, and MOS tube (Metal-Oxide-Semiconductor Field Effect Transistor, Metal-Oxide-Semiconductor Field Effect Transistor) Q2 in the virtual frame form a Boost circuit, which is provided by the driver chip The PWM signal controls the MOS tube Q2. When the MOS tube is turned on, the capacitor C1 supplies power to the LED light bar, and the source of the MOS tube is grounded through the resistor R10. [0004] In addition, the circuit further includes ...

AI Technical Summary

Problems solved by technology

[0004] In addition, the circuit further includes a current setting circuit, the current setting circuit includes a triode Q3, and parallel resistors R1 and R2 are connected between its collector and the ground, then the resistance after parallel connection is R=(R1* R2) / (R1+R2), it can be seen from this that if the resistance values ​​of the resistors R1 and R2 are different, the accuracy of the resistor with a smaller resistance value will have a greater impact on the entire resistor, resulting in an impact on the current accuracy Larger, assuming that the accuracy of each resistor is a%, if a smaller resistor is too large or too small by a%, it will cause the current accuracy to drop by a% or close to a%

Images