tny290pg problem
Posted by: pavchinna
on
hai i done 5v ,4 amps smps. using tny290pg .am getting output 5v and when i put the above 1.5amps output voltage is droping.
i put the 2.2M Resistor parallel to R1 .Now output voltage is constant and current is 3.5amps. but the problem is VR1 160v is getting hot .please suggest me what is the problem . i attached the document
Files
| Attachment | Size |
|---|---|
| TinySwitch-4_PIDesign27 (1) (1).pdf | 2.07 MB |
Hello pavchinna,
Thank you for interested in using Power Integrations product.
When you mentioned the output voltage droping with the original R1, did the power supply stopping working or it reached any steady state point.
Did you do the design with our Pi expert tool, can you share the transformer design with us.
As for the VR1 thermal issue, it might be real depended on your transformer design, especially the leakage inductance of your transformer. if you want to improve the perfromance, rather than using the TVS directly, i suggest you add damp resistor to reduce the high current spike at your TVS, you can refer to the folllowing design of one RDK board. you can try the clamp circuit in the RDK design, it should give you better thermal performance.
https://ac-dc.power.com/sites/default/files/PDFFiles/rdr399.pdf
Best Regards