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Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
Hopefully one of our resident smpsu guys will help? THIS thread has some general design guidelines, read and absorb Richie's most excellent contribution.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
excellent...
look here its gold !
Avoid boost and flyback converters as the former has a discontinuous output current and the later has both discontinuous input and output currents! These are inherently noisey in terms of EMI and the flyback can be challanging to silence in terms of EMI. The magnetic gap in flyback transformers also spews out leakage magnetic flux lines!
Go for the push-pull transformer-coupled forward converter like you said. It's easy to get working and relatively easy to stabilise. Output current ripple is also at twice the switching frequency so easier to filter out.
Use an inter-winding faraday screen between the primary and secondary sides. This should be connected to the negative rail on the input side to return all HF switching hash to the power side via the shortest possible route.
Keep the switching frequency as low as possible. Yes the magnetics will be bigger but it will be quieter.
EDIT: HA! I even called it gold then!
EDIT 2: So with the Faraday screen do i use a copper strip thats not a full turn (dont want it to be a shorted turn) wrapped between the primary and the secondary, then have it tied to the center-tap? is that what hes saying?
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
im trying to find a fixed on-time pulse posistion modulated IC. that way ill have an easier time mitigating unwanted fields.
so far, which is meant for ram chips. Ive been looking here on 4hv.org and on mouser, but i cant find my original IC that i knew did constant on-time modulation.
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Questions, Single Switch Low - voltage Flyback SMPS ...
