I do a PFC stage for 650w which use ADP1047
switch freq = 60K
Choke = 370uH
When I checked the duty cycle during the VAC pin valley @Vin=230V
Why the duty close to 95% ? Is it right ? (see the attachment , yellow for duty cycle , green for ADP1047 VAC Pin)
If it is wrong , plz suggest us how to solve this issue !! Thanks so much
By the way , It will have the same condition @Vin=115 !!
xudong Would you kindly help to check this ? Thanks !!
It is correct. I assume the PFC is running under heavy load in the test. It will run close to maximum duty at the input voltage zero voltage crossing as shown in the picture. 60KHz is a little low for 650W application, the switching frequency can go to 100KHz.