req: rectifying method for smps

[pisoiu]

Does anyone know a rectifying method for secondary output winding of a smps (of course, other than using clasic diodes), especially for low voltages/heavy loads ? Goal is to reduce dissipated power on rectifying element. Low EMI/EMC is also a concern.

/pisoiu

 

[alphi]

use mosfet for syn rectify

 

[batdin]

That's right,you should use MOSFET-based rectifier.This is useful however only if (Ron)X(I) is less than 0.5V,otherwise Shottky barrier diodes are more appropriate.
Example: BUZ11 has 0.04ohms resistance in ON state.If the amplitude of the current is greater than 10A,you should either use two MOSFETs in parallel or resort to shottky diodes.
When the curent is 200A for instance,MOSFET is not an option.
Consider the complexity of syncronous rectifiers-at least some more windings of the power transwormer.