Other Parts Discussed in Thread: UCC28051
Hi,
I am designing a 100W 24V power supply as detailed in design note tida-00701 and I have a few queries regarding the design:-
1) Page number 45 section 7.4 of the design note says that the altium project files may be downloaded from the tida-00701 webpage but I couldn't find the files there. I emailed the TI support and they told me to post on the forum and try asking the design engineers at TI's e2e forums if such files are available.
2) My second question is regarding the PFC design using the UCC28051. On page 11 section 4.2.9 "Multiplier Setup", there is an equation (equation 17) given which gives the ratio of Rac1 to Rac2. But when I plug in the values given in the schematic (page 42 figure 41), equation 17 doesn't hold true. I have assumed the following values:-
Rac1=680k+680k+680k
Rac2=8.25k
Vac(max)=265 Vac
I went through the design details given in the UCC28051 datasheet. When I plug in the values used in the schematic given in the datasheet, the equation holds true.
Please help me identify if I am making some mistake in my calculations or is there an error in the design note. I have attached the tida-00701 design note for reference.