Reverse-current-prevention protection circuit of LDO (low dropout regulator)

Abstract

The invention relates to a reverse-current-prevention protection circuit of an LDO (low dropout regulator). On the basis of an existing LDO, a reverse-current-prevention circuit and a reverse-current-prevention NMOS (N-metal-oxide-semiconductor) transistor are arranged, the reverse-current-prevention circuit is connected among an input terminal VIN, an output terminal VOUT and a substrate of a power PMOS (P-channel metal oxide semiconductor) transistor, a drain and a source of the reverse-current-prevention NMOS transistor are connected between a feedback divider resistor and a ground terminal, and VIN potential and VOUT potential are compared by the reverse-current-prevention circuit, so that a substrate of the power PMOS transistor is switched to be selectively connected with the highestpotential between VIN and VOUT, the parasitic diode effect fixed between the substrate Bo and the drain of the power PMOS transistor MP is broken, an output logic signal of the reverse-current-prevention circuit is connected with a grid of the NMOS transistor, a reverse current produced by the parasitic positive bias diode effect of the power PMOS transistor can be avoided between output VOUT andinput VIN, and loss and damage of the power PMOS transistor are effectively prevented.

Description

technical field [0001] The invention relates to an LDO linear voltage regulator, in particular to an anti-backflow protection circuit of the LDO linear voltage regulator. Background technique [0002] LDO linear regulators are widely used in portable electronic devices due to their outstanding advantages of simple structure, low cost, low noise, low power consumption and small package size. [0003] Traditional LDO such as figure 1 As shown, the peripheral components are composed of input capacitor CIN, output capacitor COUT, and load resistor RL. The chip includes an enable control circuit EN, a reference voltage VR generation circuit, an error amplifier EA, a current limiting circuit CurrentLimit, and feedback resistors RF1 and RF2. The working principle of LDO is: input enable EN signal to control whether the whole circuit is working or not, the output voltage is divided and sampled by feedback resistors RF1 and RF2 and input to the reverse end of the error amplifier EA,...

AI Technical Summary

Problems solved by technology

[0005] In order to solve the problem that the traditional LDO has no anti-backflow protection circuit, the present invention provides an anti-backflow protection circuit for the LDO linear voltage regulator, which improves the application reliability of the LDO and prevents damage under various application conditions of the LDO

Images