LNK3696 Bias not working
Posted by: nkdurgarao
on
Hi,
Schematic Attached for your reference. We are using LNK3696 for generating bias power supply for AC-DC converter. AC-DC Converter has front end PFC followed by half-bridge converter. We started testing Halfbridge converter without PFC by giving external DC supply. Bias is working perfectly for input upto 350V, above 350V bias is going to auto-restart mode.
Transformer is designed with EE20 core & primary inductance is 1.2mH with leckage inductance of 20uH. Power drawn from converter is 2W. Please let us know the issue with LNK3696.
Files
| Attachment | Size |
|---|---|
| st23-026_hybrid_ac-dc_converter-20230512_1500_0.pdf | 759.34 KB |
Hi nkdurgarao,
Good Day!
I would like to know the Input and Output specs of the Bias supply so that we can help you properly. you can also provide us the Bias transformer turns ratio and construction.
I suggest to probe below items:
- Probe Vds and Ids, check for the switching frequency. If Fs is at full frequency for 50msec, this will result to auto restart. This means that there is an overload condition.
- Probe the +15V_LS_R. Check the waveform if we can see anything abnormal.
Thanks
Regards
PI-CHLOE