TOP265EG design. Radiated emissions noise issue
Hi,
I've dsigned 18W universal input AC-DC converter with DC output voltage 12V and peak load current of 1.5A.
Attached are screenshots of radiated emissions (RE) from this power supply. The green trace represents RE
at load current of 350 mA, the blue trace represents RE at real load which is higher than 350 mA. Generally,
RE is better at higher load currents (up to 1.5A) and worse at lower currents. The worst one is at 350 mA. I tried different
transformers (from different manufacturers), no noticeable improvement was found. Could excessive noise in
150 -180 MHz spectrum be caused by chip ityself?
Comments
Thanks for your response, PI-KSAN. Yes, I used PI Expert software and yes, I've seen an15 appnote.
Also, I'm aware of DER 237 describing similar design with TOP264. Selected components for my design
are different to DER237 and selected per PI Expert generated BOM including transformer manufacturing
instructions. Is there any possibility to purchase demo board per DER237 from PI to compare radiated emissions performance at
identical load currents? If answer is positive, I'd order one immediately. Please, let me know ASAP.
Sure , let me verify whether we have any DER-237 boards and we will get back to you.
Hi PI-KSAN
Any news on availability of DER-237 boards?
We don't have any of DER-237 Boards available. If you want some, please contact our Local Sales representative near you so that they will provide you the information.
Radiated EMI Noise is not mainly caused by IC itself. there are many parameters that are involved in EMI/EMC , the switching waveforms , snubber circuits , Transformer design and for Radiated EMI Lay out makes a big difference. How did you design your power supply? Did you use any of our PI Expert software or any one of our reference DER's?
Please go through the following document:
https://ac-dc.power.com/sites/default/files/product-docs/an15.pdf