PFS712
I am using PFS712 as PFC converter.
My requirement is 12V/250W output.universal input.I am using PFS712 because it has better efficiency at light load, but on my application(PFC only),the efficiency at 20% load is only 72%. PF is only 0.6. At 100% load, efficiency is 95% and PF is 0.95.
I am using RDR-248 as reference. I try everything same as RDR-248 except C4 and C5, I am using 2200pf now.
Could you please help me on this? how to improve PF and efficiency at light load?
Thanks.
Comments
Input voltage is 230V. no parts getting warm on the board.
I returned C4 and C5 to 150pF, no help.
Could you add an extra large X-cap right across the AC inlet (e.g. >= 1 uF) and re-test efficiency? It's possible that the ripple current in the input is affecting your power measuring equipment. What are you using to measure input power?
What is the input voltage where you see 72% efficiency and PF is 0.6?
Is anything on the board getting warm?
Pls. try returning C4 and C5 to 150 pF. If they are very large, they could resonate with the differential choke L2 as the PFS sweeps through some low frequency frequency at light load. This will reduce the measured PF.