Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Y capacitor across primary and secondary of fly back converter

Status
Not open for further replies.
S

srinu9009

Junior Member level 1
Joined
Sep 4, 2008
Messages
18
Helped
4
Reputation
8
Reaction score
1
Trophy points
1,283
Activity points
1,393
Hi,

i have seen some flyback converters designed circuits in that Y-Cap is using across primary and secondary winding of isolation transformer.I observed that either priamry side or secondary side operating at high voltages.For example priamry voltage is 300V DC and Secondary is 48V DC.

Let me know what is purpose of that y-cap across pri and sec of transformer?

For suppose if we will not use y-cap in that place what will happen?

Thanks
Srinivas
 

The Y1 cap is usually from the +HVDC of the pri side (but can be from the 0V-HVDC) to the neg o/p of the sec side, the idea is for VHF common mode currents to be bypassed by this cap and therefore have less common mode current flow in the mains wires, helping the psu meet RFI/EMC stds.
Regards, Orson Cart.
 
Hi Orson Cart

Thanks for your reply.is it possible to explain in detail operation with some example?

Regards
Srinivas
 

I've seen another couple of applications, a zero voltage switching or quasi resonant supply uses a cap accross the primary to make the winding resonate, I wouldnt expect one accross the secondary though.
The other while not strictly accross the winding is where a coil is driven by a half bridge and the other side of the winding from the switching trannys is connected to the power rails by a couple of caps, the idea to balance out any dc formed by non symetrical switching.
Orson cart's description is more likely though, esp if there is a cap on both pri and sec.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top