Over-power protection method for switch power supply and cuicirt

Abstract

A MOS (metal oxide semiconductor) integrate circuit that is overpower protection method and the circuit in the switch power, the electric current is proportional with the Vopp that reflects the current change on the AC line; the pressure is proportional with the Vac that reflects the pressure change on the AC line, the invention takes the pressure signal Vac from the sub-grade of the AC main transformer by the bleeder chain, then takes the pressure signal Vopp from the initial-grade of the AC main transformer by the bleeder chain, the process of the overpower estimation is two conditions: first, when the current and pressure on the AC are all higher and reaches a definite value (2.06v), maintains a definite time (7ms), happens overpower and close power; second, when the current on the AC is higher and reaches a definite value, happens overpower and close power.

Description

technical field [0001] The invention relates to a MOS integrated circuit, in particular to an overpower protection method and circuit in a switching power supply. The method and circuit are mainly used for overpower protection of switching power supplies, such as applied to power management chips as overpower protection. Background technique [0002] With the development and popularization of modern electronic and electrical technology, switching power supply is becoming more and more important, and safety is the primary factor to be considered in switching power supply. [0003] At present, the working principle of the switching power supply is to convert the input higher alternating voltage (AC) into the lower direct current voltage (DC) required for operation by operating a high-frequency switching circuit. Its working process is: when the mains power enters the switching power supply, it first passes through the choke coil and capacitor filtering to remove high-frequenc...

AI Technical Summary

Problems solved by technology

[0015] The invention provides an overpower protection method and circuit used in a switching power supply, the purpose of which is to solve the problem of poor reliability of overpower protection in the existing switching power supply, especially to solve the problem of overpower protection in the process of AC voltage establishment and power-off. Power protection issues, so that the switching power supply can reliably protect against overpower for any AC input level

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