Capacity discharge method and circuit

Abstract

In one embodiment, a method of controlling a capacitor discharge for a switching power supply, can include: (i) generating a first voltage signal from a voltage at an X capacitor that is coupled between input terminals of the switching power supply; (ii) activating a detection signal in response to the first voltage signal being inactive for a duration of a predetermined time interval, where the detection signal being activated indicates a cut-off of the input terminals; and (iii) at least partially discharging the X capacitor after the cut-off and in response to activation of the detection signal.

Description

technical field [0001] The invention relates to the field of power supplies, more specifically, to a capacitor discharge method and a discharge circuit applied to switching power supplies. Background technique [0002] At the input end of the AC power supply of the switching power supply, an X capacitor is generally connected in parallel between the live wire and the neutral wire as a safety capacitor to suppress EMI conduction interference (mainly to suppress differential mode interference). In some occasions, due to actual needs, The capacitance of the X capacitor is often relatively large, so that after the AC power is cut off, the X capacitor will store high-voltage electric energy for a long time, and the safety standard stipulates that within two seconds after the AC power is cut off, the voltage of the input terminal of the power supply must drop to 30% of the original rated working voltage, so in order to meet the requirements of safety standards, the X capacitor nee...

AI Technical Summary

Problems solved by technology

[0004] In view of this, the present invention provides a capacitor discharge method and a discharge circuit, which are applied to switching power supplies to solve the problem of high energy consumption caused by X capacitor discharge circuits in switching power supplies in the prior art

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