A pulse width modulation switching power supply controller and switching power supply

Abstract

The invention provides a pulse width modulation switching power supply controller and a switching power supply and belongs to the technical field of electronic integrated circuits. The pulse width modulation switching power supply controller and the switching power supply are widely applied to a PWM (Pulse Width Modulation) mode AC / DC (Alternating Current / Direct Current) switching power supply system. The PWM controller comprises an FB (Feed Back) sampling circuit, a current mode selecting circuit, a square wave generating circuit and the like. The pulse width modulation switching power supply controller has the advantages of being capable of achieving self-adaption of the system working frequency under different loads and reducing standby power consumption of the switching power supply.

Description

technical field [0001] The invention relates to the technical field of basic electronic circuits, in particular to a pulse width modulation switching power supply controller and a switching power supply. Background technique [0002] With the increasing awareness of global environmental protection, more efficient use of energy has become a global consensus, so in recent years electronic products and their power supplies have begun to be restricted by energy-saving regulations, such as the California Energy Commission (CEC) Energy-saving regulations, and the "Energy Star (Energy Star)" label program, etc. In addition to these energy-saving specifications, another new specification that has attracted attention is "standby power consumption." According to statistics, the power consumption of electronic products in standby mode accounts for 3%-13% of the world's electricity, so the power consumption in standby mode has also drawn up clear specifications, and low standby power c...

AI Technical Summary

Problems solved by technology

However, due to the inevitable loss of energy in the working process of the switching power supply, including switching loss, conduction loss and control circuit loss, and these losses have a great relationship with the operating frequency of the system, especially when it is light-loaded or no-loaded, Using the same switching frequency as under heavy load will greatly reduce the ratio of useful power to total power and reduce efficiency

And with the increase of switching power supply operating frequency caused by the trend of product miniaturization, the energy loss is also increasing, which has become the most important part of the energy loss of the switching power supply system under light load and standby state

[0003] It can be seen that there is a problem in the prior art: the high standby power consumption of the existing AC / DC switching power supply

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