What's the purpose of the Y capacitor?
Hi!, I'm trying to develop a laboratory power supply so I need that the supply be completely isolated from the hot side but the PIExpert software show me a circuit whit a capacitor connected from the GND of the cold side to the VCC(312Vcc) hot side.
Is a small capacitor but...
I can't find any document explaining that, Would you suggest one please?
Another problem that I have is that in my country I can't find the new products from Power Integrations, the suitable components that I find here is from the family of TOP245, ie. or TOP220.
There's any way of get an older version of the PI designer?
Comments
Thanks!
Pd. The captcha is F* annoying
Running off the internal website and being an employee, I don't have to deal with any Captcha's. If you can take a screen shot though and give me some feedback, I will forward your thoughts and suggestions to the web design team. We're constantly improving and updating the webiste. Maybe we can make a minimal change that would make everyone happier with the process.
-The Traveler
Here a sample.
The second one is specially annoying.
At least Can be NOT case sensitive?
Thank you for the feedback. I went ahead and sent off your feedback and screenshots to the web design team.
-The Traveler
Sidens -
The purpose of the Y-capacitor is to help with passing conducted EMI. It's not a strict requirement for any design, it's functional purpose is to direct high-frequency noise from the output back to Line/Neutral so that those high-frequency currents don't pass through the earth/ground connection.
Several of our designs don't require a Y-cap:
http://www.powerint.com/sites/default/files/PDFFiles/der279.pdf
http://www.powerint.com/sites/default/files/PDFFiles/di158.pdf
http://www.powerint.com/sites/default/files/PDFFiles/di157.pdf
http://www.powerint.com/sites/default/files/PDFFiles/di159.pdf
http://www.powerint.com/sites/default/files/PDFFiles/der207.pdf
http://www.powerint.com/sites/default/files/PDFFiles/der267.pdf
http://www.powerint.com/sites/default/files/PDFFiles/der265.pdf
You'll notice that these are mostly lower power designs and the reason for this is mostly in the transformer design. Depending on your application, EMI requirements, power levels, etc, you might be able to get away with not using the Y-cap. PI Expert defaults to using a Y-cap...but if you enable the E-Shield option in PI Expert (under the primary/bias/secondary winding options) it might be able to generate a design without the Y-cap.
Our patented E-Shield technology is a specialized transformer winding technique that is used to significantly minimize primary to secondary winding capacitance within the transformer. When implemented correctly, the interwinding capacitance can be reduced enough, that for some applications, a Y-Cap becomes unnecessary for passing conducted EMI.
For a better explanation of our E-Shield technology, check out Puzzler #8 in our design support section. It has a pretty nice explanation of how the technique works and how to implement it.
http://www.powerint.com/en/community/documents-quizzes/puzzler-8
I hope this answers your question. If you need any other assistance, please let me know.
-The Traveler