flickering at 260v and above

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Hi,

we made a non dimmable 28W (70V/400mA) driver with guidance of DER286. It is works good but flickering at 260volts and above. Ckt is having all components same as of der286 except the output rectifier which used MUR460. Transformer used PQ2625 and design spread sheet shows no warning. We put  KP = 0.8 and VOR = 116V and switch is LNK419. It is working from 80V to 260V without any issues. Can you gude us to solve the the FLICKERING PROBLEM @260V. Pls note the Feedback pin  current is 160uA upto 264V. We added  RV2 - 1.4M ohms and found no change  in the flickering.

 

Waiting for your immediate reply

DMS 

If the RV is set to 4Meg, then it should not be the one causing the flicker. Please remove the output over-voltage protection circuit if you have one to check if it's the one causing the problem.

 

You may try to use a lower R9 value to increase the BP current supply.