Direct-current voltage conversion circuit and liquid crystal display device

Abstract

The present invention provides a direct-current voltage conversion circuit and a liquid crystal display device. The direct-current voltage conversion circuit includes a voltage division unit, a voltage conversion unit, a first subtracter, an adder, a second subtracter and a pulse width modulation unit; the pulse width modulation unit is used for adjusting the duty ratio of pulse signals outputted by the pulse width modulation unit when a voltage outputted from the output end of the second subtracter is smaller than or greater than a preset voltage difference value, so that an output voltage and a feedback voltage can be increased or decreased until the voltage outputted from the output end of the second subtractor is equal to the preset voltage difference value, and therefore, the output voltage of the direct-current voltage conversion circuit can be increased when current outputted from the direct-current voltage conversion circuit is increased, and the output voltage of the direct-current voltage conversion circuit can be decreased when the current outputted from the direct-current voltage conversion circuit is decreased, and thus, the output voltage of the direct-current voltage conversion circuit can be kept consistent with a voltage received by an electric component connected with the direct-current voltage conversion circuit, and the quality of a product can be improved.

Description

technical field [0001] The invention relates to the field of display technology, in particular to a DC voltage conversion circuit and a liquid crystal display device. Background technique [0002] With the development of display technology, liquid crystal display (Liquid Crystal Display, LCD) and other flat display devices are widely used in mobile phones, TVs, Various consumer electronic products such as personal digital assistants, digital cameras, notebook computers, and desktop computers have become the mainstream of display devices. [0003] Most of the liquid crystal display devices currently on the market are backlight liquid crystal display devices, which include a liquid crystal display panel, a backlight module and a circuit board. The working principle of the liquid crystal display panel is to pour liquid crystal molecules between the thin film transistor array substrate (Thin Film Transistor Array Substrate, TFT Array Substrate) and the color filter substrate (C...

AI Technical Summary

Problems solved by technology

[0005] At present, the size of TFT-LCD tends to increase day by day, and the current in each DC voltage conversion circuit is getting larger and larger. With the increase in the need to reduce costs, each DC voltage conversion circuit to its corresponding electrical components Due to the limitation of the board width of the printed circuit board, the width of the traces between the DC voltage conversion circuit and the corresponding electric components is limited, which will make the traces have a large resistance, while the current In very large cases, the output voltage of the DC conversion circuit will produce a large voltage drop at the wiring, and the voltage received by the electrical components cannot meet the demand. For example, if the output voltage of the DC voltage conversion circuit is 1.8V, the wiring The impedance of the line is 0.5Ω, and the current is 0.5A, so the actual input voltage of the electrical component is only 1.55V, which cannot meet the demand

If the input voltage is directly set high, when the current is small, the voltage of the input power-consuming element will be too large and exceed its upper voltage limit

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