Low dropout linear regulator based on constant power protection

Abstract

The invention discloses a low-dropout linear voltage regulator based on constant power protection, comprising: an LDO unit, including an error amplifier AMP, a MOS transistor MP, and voltage dividing resistors Rf1 and Rf2, and the load current in the LDO unit is IL; the first voltage The detection unit is used to output the first voltage V1, which includes a number of current mirrors and resistors; the second voltage detection unit is used to output the second voltage V2, which includes MOS transistors MS and resistors; the constant power protection unit includes an analog multiplier , a comparator and a MOS tube PM5, the analog multiplier is used to multiply the first voltage V1 and the second voltage and output Vp, the comparator is used to compare Vp with the preset power value Vrefp, and control it through the MOS tube PM5 according to the comparison result Whether the LDO unit is working. The present invention uses two voltage detection units and a constant power protection unit. When the output of the LDO unit is overcurrent, the actual output current IL can be calculated according to the set power P and the value of VDD-VOUT, and the LDO unit can be intuitively and Linear protection.

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...

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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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