I'm designing a buck converter with these requirements:
- Input voltage: 120-690Vrms AC (three phase) 50/60Hz
- Output: 50V/200mA (max)
To meet the high voltage requirements, the reference design uses a balancing network of three 400V capacitors, which may be expensive.
For my application following the controller datasheet, I calculated a minimum capacitance of 10 uF. However, I'm considering if I really need it. For example, this another Reference Design based on flyback topology doesn't use bulk input capacitors, just ceramic ones. But I think that applies if I always have three phase, right? If it happens that only two phases are available, then may I run into issues? What do you suggest?