An anti-magnetic interference switching power supply and its control circuit and control method

Abstract

Disclosed are a switching power supply, a control circuit and a control method thereof. The control circuit includes an error amplification unit that provides an error amplification signal according to the output voltage of the switching power supply, a magnetic field detection unit that judges whether the switching power supply is affected by an external magnetic field and provides a magnetic field detection signal, a frequency control unit that provides a clock signal according to the magnetic field detection signal, and A switch control unit that provides a switch control signal to control a main power switch in the switching power supply, wherein the switch control unit controls a duty cycle of the main power switch in response to the error amplification signal and controls a switching frequency of the main power switch in response to a clock signal. Compared with the prior art, while realizing the controllable switching frequency, the interference of the external magnetic field to the switching power supply can be eliminated or weakened, and the invention has a simpler structure and lower cost.

Description

technical field [0001] Embodiments of the present invention relate to an electronic circuit, and more specifically, to a switching power supply. Background technique [0002] Switching power supply has been widely used in various fields due to its advantages such as fast transient response and low loss. However, when it is applied to fields such as electric meters, it will face the problem that there may be interference from an external strong magnetic field. An existing solution is to add a mechanical shielding shell to shield the interference of the switching power supply from the external strong magnetic field. The disadvantage of this method is that it increases the cost and volume. Another existing solution is to leave a very large margin when designing the magnetic components in the switching power supply, such as when designing an inductor or a transformer. This method will lead to a very large volume of the magnetic components in the switching power supply. It also...

AI Technical Summary

Problems solved by technology

However, when it is applied to fields such as electric meters, it will face the problem that there may be interference from external strong magnetic fields

An existing solution is to add a mechanical shielding shell to shield the interference of the external strong magnetic field on the switching power supply. The disadvantage of this method is that it increases the cost and volume

Another existing solution is to leave a very large margin when designing the magnetic components in the switching power supply, such as when designing an inductor or a transformer. This method will lead to a very large volume of the magnetic components in the switching power supply. also increased cost

Images