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Poor load regulation

Posted by: lalani2009 on

Hello ,

I am designing 85W(48V / 1.75A) SMPS for my application using TOP257EN on 132KHz design. I had designed it using PI Expert software.It work properly in no load condition(230V/50Hz input) like , 48 V output;short circuit shutdown ; low input voltage shutdown. Means all part of circuit in off load condition works perfect. But it gives only 26V in on load condition with 1A load. I had tested Primary side of transformer and every thing was correct but I can't find fault on secondary side or feedback part.Circuit implementation , transformer parameter values, feedback network design all are correct.

I had attached my design with this post

So , please give me some trouble shooting guide to solve this problem.........

Thanks.

Files

Attachment Size
TOPSwitch-HX_PIDesign2_0.uds 235 KB

Comments

Submitted by PI-Cochrane on 05/16/2012

it is possible that the load regulation is caused by R9, PLS try a higher value resistor for R9. Another thing you need to double check is if the tl431 can handle 48V.

Thanks for using PI part.