Soft starting circuit applied in charge pump

Abstract

The invention discloses a soft starting circuit applied in a charge pump, comprising a current source, a buffer drive unit, a first control switch, a second control switch, and a transistor. A grid electrode of the transistor is mutually connected to a drain electrode. At the soft starting stage of the charge pump, the second control switch switches off the pulling-up function of a driving module,which is used for driving the grid electrode of a power pipe of the charge pump. When the first control switch is under the switching-on state, the current of the current source flows into the transistor, and the grid electrode of the transistor generates grid voltage, and the grid voltage is sent to the grid electrode of the power pipe through the buffer drive unit, and the power pipe is started. When the first control switch is under the switching-off state, the grid electrode of the transistor generates grid voltage, which is stopped, and the driving module pulls the grid potential of thepower pipe to a low potential, and the power pipe is switched off. The transistor adopts a diode connecting mode to receive the current of the current source, and generates the grid voltage. Under thestate that the current of the current source is too small, the charge pump can be effectively and softly started.

Description

technical field [0001] The invention relates to the technical field of charge pump driving, in particular to a soft start circuit applied to the charge pump. Background technique [0002] A charge pump, also known as a switched capacitor voltage converter, is a DC-DC converter that uses a bootstrap capacitor to store energy. Charge pumps can step up or down the input voltage and can also be used to generate negative voltages. [0003] see figure 1 , wherein the charge pump 3 is a schematic structural diagram of the charge pump in the prior art, including four power transistors (switching transistors) including S1, S2, S3 and S4, and a capacitor Cfly and a capacitor Cout. [0004] Q1 and Q2 are two non-overlapping clock signals, wherein the clock signal Q1 controls the power transistors S1 and S3 to be turned on and off; the clock signal Q2 controls the power transistors S2 and S4 to be turned on and off. [0005] When the clock signal Q1 is high, that is, when Q2 is low, ...

AI Technical Summary

Problems solved by technology

[0012] Aiming at the deficiencies of the prior art, the present invention proposes a soft-start circuit applied to the charge pump, the transistors of the circuit receive the current of the current source in the form of a diode connection, and then generate the current used to control the grid of the power transistor S1 in the charge pump. Gate voltage, the gate voltage is only related to the current in the transistor, which solves the problem that the existing soft-start circuit cannot effectively start the power tube when the current source current is too small

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