Joerg, The best topology for your 75W PFC, 35 Vout AC to DC converter is a standard PFC Boost converter followed by an isolated, 200V to 35V LLC converter. Each stage should yield 0.94% efficiency with an overall 88% total efficiency. The PFC boost converter is a simple 8 pin device and the LLC is a 12 pin sip with the bridge included. You probably need holdup time and this gives it to you. The LLC is ZVS to reduce CM output noise and can be run at fixed frequency and sync to the front end PFC to reduce bulk cap ripple current. Lots of room for improvement not found in a simple flyback.I can help on ways to simplify your LLC design. Your Flyback design is a disaster waiting to happen. Remember, when in doubt, HAC. (Hire a Consultant) Cheers, Harry
- posted
9 years ago