Differerent connection for Y-capacitor (EMI filter) in SMPS

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Hi

What is the difference between these two connections Y-capacitor (EMI filter)?
*high-voltage side to isolated 12V DC output *isolated 0V DC output rail and a "GND"
Could you tell me the raison of each connection ?and what the right way to do that ?

첨부 파일Size
Capture2.JPG27.33 KB
Capture.JPG26.84 KB

Hi pinhas,

Both Y-cap connections shown are valid. In each case, the key is to place the Y-cap across primary and secondary domains by connecting to "quiet" nodes, i.e. avoiding connections to switching nodes for diodes or FETs. For example, in Capture2.jpg, we avoid connecting to D6, and in Capture.jpg, we avoid connecting to D3.

-PI-ODO