AC/DC voltage converting circuit with low stand-by power consumption and control method thereof

Abstract

The invention provides an alternating current(AC) / direct current (DC) voltage converting circuit with low stand-by power consumption, which comprises a safety capacitor, a common mode filter inductor, a rectifier bridge, a filter and a switching power supply circuit which are connected in parallel in sequence, wherein the safety capacitor receives input power, and the input power is processed by the common mode filter inductor, the rectifier bridge and the filter and then input to the switching power supply circuit; the switching power supply circuit comprises a power stage circuit, a control circuit and a phantom load, and the control circuit is used for detecting whether the input power works normally and controls the power stage circuit to perform voltage conversion on the input power; when the input power is in a normal working state, the phantom load is removed; and when the input power is in an under-voltage locking working state, the phantom load is loaded to perform discharging on the safety capacitor. The AC / DC voltage converting circuit solves the problem of power consumption caused by the direct addition of discharge resistance in the prior art, reduces the cost of a switching tube and is favorable for circuit integration.

Description

technical field [0001] The invention belongs to the field of switching power supplies, in particular to an AC / DC voltage conversion circuit with low standby power consumption and a control method thereof. Background technique [0002] Switching power converters are used to convert AC power into DC power, and are widely used in electronic devices. If ordinary capacitors are used at the power inlet of the switching power converter, when the AC power is cut off, the charge of the ordinary capacitor will remain for a long time after the AC power is disconnected. Special X-type safety capacitors instead of ordinary capacitors [0003] Such as figure 1 Shown is the circuit diagram of a conventional isolated switching power converter. The isolated switching power supply converter includes a safety capacitor Cx, a discharge resistor Rx, a common mode filter inductor, a rectifier bridge, a filter and a switching power supply circuit connected in parallel in sequence, and the switc...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide an AC / DC voltage conversion circuit with low standby power consumption and its control method to solve the problem of power loss caused by directly adding a discharge resistor in the prior art, and to ensure that the safety capacitor Cx can be safely fast discharge

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