Low Dropout Linear Regulators

Abstract

An LDO (low dropout regulator) comprises anovervoltage power device, a voltage detection circuit, a first control circuit and a second control circuit, wherein the voltage detection circuit is suitable for detecting power voltage to produce a detection signal, and the detection signal is output by the voltage detection circuit; the first control circuit is suitable for controlling the detection signal according to a control signal, so that the detection signal is of first logic level in preset time interval after power on and is of second logic level different from the first logic level after the preset time interval; the second control circuit is suitable for controlling the overvoltage power device according to the detection signal, controls the overvoltage power device to be switched off in response to the detection signal being of the first logic level and removes control on the overvoltage power device in response to the detection signal being of the second logic level. Surge voltage output by the LDO can be inhibited effectively with adoption of the scheme.

Description

technical field [0001] The invention relates to the field of power supply design, in particular to a low-dropout linear regulator. Background technique [0002] Low dropout linear regulator (LDO, Low Dropout Regulator) is a linear regulator, it has many advantages such as low cost, low noise, small quiescent current, etc., and the peripheral circuit of low dropout linear regulator is less, Usually only need one or two bypass capacitors, simple and easy to use. In addition, the output stage of the low-dropout linear regulator usually includes a bypass device, which can also be called an overvoltage power device. The overvoltage power device generally uses a bipolar transistor or MOS transistor operating in the linear region, from the input A certain voltage is subtracted from the voltage and produces a regulated output voltage. Taking a positive output low dropout linear regulator as an example, its overvoltage power device usually uses a PNP transistor or a PMOS transistor...

AI Technical Summary

Problems solved by technology

[0004] In the prior art, in order to avoid the sharp increase of the power supply voltage, a decoupling capacitor is usually provided between the power supply and the ground of the low dropout linear regulator 100, but the decoupling capacitor cannot fundamentally eliminate The surge voltage

[0005] Therefore, the problem that the low-dropout linear regulator in the prior art will output a large surge voltage at the moment of power-on needs to be solved urgently.

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