NOISE CANCELING CIRCUIT OF SWITCHING POWER SUPPLY

摘要

Disclosed is a noise canceling circuit of a switching power supply, comprising a transformer (T), wherein a primary winding (T1) thereof is connected with an AC input end (10), and a secondary winding (T2) thereof is connected with a DC output end (20). The noise canceling circuit further comprises at least one group of symmetric Y capacitors. In the at least one group of symmetric Y capacitors, a first Y capacitor (CY1) is respectively connected to a positive input end of the AC input end (10) and a negative output end of the DC output end (20), and a second Y capacitor (CY2) is respectively connected to a negative input end of the AC input end (10) and the negative output end of the DC output end (20). The noise canceling circuit not only can cancel the noise, but also has high efficiency and desired EMC performance.