DC step-down circuit and DC step-down method

Abstract

The present invention provides a direct current buck circuit and a direct current buck method. When the direct current buck circuit of the present invention works, an input voltage gradually rises from 0; when the input voltage rises to be greater than or equal to a startup voltage and be less than a working voltage, a first output end of a buck control module outputs a reference voltage, and a startup control module connects the input end and the output end thereof so as to ground the control end of the buck control module, so that the second output end of the buck control module outputs 0; when the input voltage continues to rise until being greater than or equal to the working voltage, the startup control module disconnects the input end and the output end thereof so as to disconnect the control end and the grounding end of the buck control module; thereafter, when the buck control module charges the control end thereof to be greater than or equal to a soft startup voltage, the second output end of the buck control module outputs a control signal to control a power conversion module to output an output voltage as a target voltage. Therefore, the present invention can avoid that current in an MOS tube in the circuit is excessive when the input voltage is too low and a load is large.

Description

Technical field [0001] The present invention relates to the field of display technology, in particular to a DC step-down circuit and a DC step-down method. Background technique [0002] With the development of display technology, flat-panel display devices such as liquid crystal display (Liquid Crystal Display, LCD) have been widely used in mobile phones, TVs, etc. due to their high image quality, power saving, thin body and wide application range. 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 Fil...

AI Technical Summary

Problems solved by technology

During the rise of the input voltage VIN, when the input voltage VIN is very low and the output load is large, the current in the field effect transistor (MOS transistor) in the DC step-down circuit is relatively large, which is easy to trigger the overcurrent protection and cause The circuit cannot work normally, and in the process of dropping the input voltage VIN, when the input voltage VIN is very low and the output load is large, the circuit in the MOS tube in the DC step-down circuit is large and prone to burning problems

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