Multi-mode switching method of switching power supply and switching power supply

Abstract

The invention discloses a multi-mode switching method of a switching power supply and the switching power supply. The multi-mode switching method of the switching power supply is characterized in that a mode selecting pin is additionally arranged on the switching power supply to receive an externally input mode selecting signal; a control module for controlling a switching tube to be connected and disconnected is used for limiting the type of an output modulating signal according to the mode selecting signal, so as to limit the working mode of the switching power supply. According to the multi-mode switching method of the switching power supply and the switching power supply, the mode of adding external input voltage is adopted to control the switching power supply to be selectively switched under the supported various working modes, and after the working mode is selected, the switching power supply is forcible to be worked under such mode without being influenced by the change of load current; therefore, the generality of the switching power supply is improved, one switching power supply can work under various modes, and as a result, different design requirements of different systems can be met; in addition, the working mode of the switching power supply cannot change along with the load current in some special application place, and therefore, the special application demands of some places can be met.

Description

technical field [0001] The invention belongs to the technical field of switching power supplies, and in particular relates to a control method for selectively switching a switching power supply in multiple operating modes and a switching power supply designed based on the switching control method. Background technique [0002] A switching power supply is a power supply that uses modern power electronics technology to keep its output voltage constant by controlling the time ratio of the switch tube being turned on and off. components such as circuits. [0003] Current switching power supplies can be divided into voltage / current control methods, hysteresis control methods, constant on-time control methods, etc. according to different control methods. Among them, the voltage / current control method requires an internal clock. Based on the different modulation modes, it can work in Pulse Width Modulation (PWM), Pulse Frequency Modulation (PFM) or skip cycle modulation mode (Pul...

AI Technical Summary

Problems solved by technology

This design method requires technicians to select a suitable switching power supply for the specific design of the system circuit according to the actual load conditions of the application in advance, which has poor versatility and increases the workload of technicians.

Even some switching power supplies can adaptively change their working mode according to the change of load current, but for some applications that need to force the switching power supply to work in a specific mode, this switching power supply still cannot meet the application requirements

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