Charge pump and liquid crystal display screen driving chip

Abstract

The invention relates to a charge pump and a liquid crystal display screen driving chip. The charge pump comprises a first capacitor, a second capacitor, a first charging branch, a second charging branch, a first booster branch, a second booster branch and a first switch, wherein the first charging branch charges the first capacitor when a first clock is valid, the second charging branch charges the second capacitor when a second clock is valid, and the first clock and the second clock are a pair of non-overlapping clocks; the first booster branch boosts and outputs the voltage of an upper pole plate of the first capacitor outwards when the second clock is valid, and the second booster branch boosts and outputs the voltage of an upper pole plate of the second capacitor outwards when the first clock is valid; the first switch is controlled by a third clock and is connected with a lower pole plate of the first capacitor and a lower pole plate of the second capacitor, the third clock is valid when the first clock and the second clock are invalid and is not overlapped with the first clock and the second clock, and charges between the first capacitor and the second capacitor can be shared when the third clock is valid. The charge pump has the advantages of higher conversion efficiency and less ripple wave.

Description

technical field [0001] The invention relates to a voltage converter, in particular to a charge pump and a liquid crystal display drive chip. Background technique [0002] A charge pump is a DC-DC (converter) that uses so-called "flying" or "pumping" capacitors (rather than inductors or transformers) to store energy. Its internal transistor switch array controls the charging and discharging of the flying capacitor in a certain way, so that the power supply voltage is multiplied or reduced by a certain factor (for example: -1, 2 or 3), so as to obtain the required output voltage. [0003] Various charge pump circuits are known in the prior art. figure 1 It is a schematic circuit diagram of a common voltage doubler charge pump in the prior art. The prior art charge pump comprises four switches S1, S2, S3, S4 and a capacitor C1. Such as figure 2 As shown, the switches S1 and S2 are controlled by the first clock, and the switches S3 and S4 are controlled by the second clock....

AI Technical Summary

Problems solved by technology

Such a charge pump circuit is limited by the chip area and it is more difficult to obtain better energy efficiency and output ripple

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