Low dropout linear regulator based on constant power protection

Abstract

The invention discloses a low dropout linear regulator based on constant power protection, comprising: an LDO unit comprising an error amplifier AMP, an MOS transistor MP and divider resistors Rf1 andRf2, a load current in the LDO unit being IL; a first voltage detection unit, used for outputting a first voltage V1 and comprising a plurality of current mirrors and resistors; a second voltage detection unit used for outputting a second voltage V2 and comprising an MOS transistor MS and a resistor; a constant power protection unit, comprising an analog multiplier, a comparator and an MOS tube PM5, the analog multiplier being used for multiplying the first voltage V1 and the second voltage and outputting Vp, and the comparator being used for comparing the Vp with a preset power value Vrefp and controlling the LDO unit to work or not through the MOS tube PM5 according to the comparison result. Through the two voltage detection units and the constant power protection unit, when overcurrentis output by the LDO unit, the actual output current IL can be calculated according to the set power P and the VDD-VOUT value, and the LDO unit can be visually and linearly protected.

Description

technical field [0001] The invention belongs to the technical field of low-dropout linear voltage regulators, and in particular relates to a low-dropout linear voltage regulator based on constant power protection. Background technique [0002] Low dropout regulator (LDO) has the advantages of low output noise, simple circuit structure, small chip area occupation and small voltage ripple, etc., and has become an important circuit in power management chips. Low-dropout linear regulators can provide power with low output ripple for noise-sensitive circuits such as analog circuits and radio frequency circuits, and because of their relatively simple structure and few peripheral components, they are widely used in SoCs. [0003] ginseng figure 1 As shown, the LDO in the prior art mainly includes an error amplifier AMP, a MOS transistor MP, voltage dividing resistors Rf1 and Rf2, and a load (the load current is IL). The basic principle of LDO is: the error amplifier AMP is used t...

AI Technical Summary

Problems solved by technology

[0004] In the prior art, when the LDO is over-current, the protection will not start until the preset current protection point is reached, but this over-current point will vary greatly with different chips and different conditions, so power over-current may occur. Large and burnt chips, especially high-voltage input circuits, may also cause the current to fail to come out, and for chip users, it is impossible to intuitively understand the current capability of the chip, which will bring unnecessary trouble to the use

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