Noise on TNY-278PN
Hello everybody! I have a project for a smps 13.8 V x 1 A with a universal input (85VAC-265VAC). I did the design in PI Expert using TNY-278PN and transformer E20/10/5. I built the circuit and it worked well at low loads. However, when I put higher loads (500 mA), the processor generates an audible noise. The voltage is stabilized, however such noise occurs. I even wrapped the transformer, but did not apply the varnish. Does the application of varnish the noise does not occur?
Can someone help me?
Comments
Hello!
I had read this AN. I did two things: I applied glue in the middle of the core EE and varnish applied to the transformer.
The noise disappeared. Had not used the Tiny family 3 and I like it very ...
Could anyone tell me what the basic difference between using the winding with BIAS or not? The difference is only in consumption?
Hi:
As the TinySwitch-III devices are completely self-powered, there is no requirement for an auxiliary or bias winding on the transformer.
However by adding a bias winding, the output overvoltage protection feature can be confi gured, protecting the load against open feedback loop faults. Moreover, providing bias winding can decrease the no-load consumption to well below 50 mW.
Hi,
Yes, the varnished transformer will help a lot to eliminate the audiabe noise. Plesae varnish the transformer, see if the audiable noise goes away.
There is also an application note available in our website taking about the audiable nosie suppression, please find it in the following link:
http://www.powerint.com/sites/default/files/product-docs/an22.pdf
This will help you to understand the cause of the audiable noise and the way to improve and eliminate it.