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Regarding Audible noise Issue in 30V 3.6A SMPS

Posted by: prakash gundale on

Dear Sir,we have designed 30V 3.6A SMPS by using PI expert software,now we are facing the audible noise issue at full load condition for 85VAC to 230VAC input supply, at present we are reffering AN-47 of power integration,which suggest following points to resolve the audible noise issues. ·         Change the snubber capacitor from ceramic to polyster film capacitior

·         Maximum Operating Flux Density (Bm) recommended value as per AN-47  is 3000 Gauss, but as per PI expert design it is coming as 2566 Gauss.

 ·         Audible noise can be reduced/eliminated by reducing flux swing (delta B) in transformer at peak current by changing transformer design( by increasing core cross sectional area and/or primary turns)      out of these points the first point i.e snubber capacitor is changed from Ceramic Disc to Polyster Film Capacitor, but no improvement was there for this audible noise issue, so shall we go for remained two points as mention above or if you have any suggestion for this noise issue please suggest us ASAP, Thanks & Regards,Prakash Gundale+91 7385983695

Comments

Submitted by PI-Surak on 02/26/2013

At full load audible noise would suggest unstable loop. Check transient rresponse and look for signs of oscillation at output