Switch voltage-stabilizing circuit and control method thereof

Abstract

The invention discloses a switch voltage-stabilizing circuit which can regulate switching frequency as well as current peak, has high efficiency and has no audio-frequency noise generated in a state of light load, and method thereof. The switch voltage-stabilizing circuit comprises an energy storage component capable of storing energy; a switch electrically coupled to the energy storage component, wherein the energy storage component can store energy when the switch is on, and the energy stored in the energy storage component is transmitted to a load when the switch is off; a control circuit electrically coupled to the switch, wherein the control circuit compares current flowing through the switch with a current threshold, when the current flowing through the switch is more than the current threshold, the switch is off, and the control circuit determines on and off time of the switch according to the load of the switch voltage-stabilizing circuit, when the load becomes big, the on and off time of the switch is reduced, and when the load becomes small, the on and off time of the switch is increased. The current threshold is constant when the circuit has no light load and becomes low with the load reduced when the circuit has light load.

Description

technical field [0001] The present invention relates to a power supply circuit, in particular to a switching voltage stabilizing circuit and a control method thereof. Background technique [0002] Many electronic devices today require DC voltage to be powered, and this DC supply voltage usually comes from an adapter. The adapter obtains AC voltage from the wall socket, converts the AC voltage into an uncontrolled DC voltage through a rectifier bridge, and converts the uncontrolled DC voltage into a required DC power supply voltage through a switching power supply. [0003] Switching power supplies usually use transformers or inductors as energy storage elements. For example, a transformer is used as an energy storage element in a flyback converter. A switch is electrically coupled to the primary side of the transformer, and the control circuit controls the switch to be turned on and off, so that energy is alternately stored or transmitted in the transformer. to the seconda...

AI Technical Summary

Problems solved by technology

If the switching frequency is kept constant and the current peak value is adjusted, such as traditional peak current control, the efficiency of the switching power supply will be greatly reduced under light load conditions.

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