Hi. I'm trying to minimise loses in a boost converter. Switching period ~10us, Iavg~15A,, Ipk~20A, L=10uH, Vout = 45V(max). I have a highside FET across the flyback diode, and so the diode is only conducting for ~500ns per cycle between switches. However the flyback diode is getting surprisingly hot.
When designing the circuit I focused on the diode's voltage drop and choose a Vishay SS36 (http://www.vishay.com/docs/88751/ss32.pdf). But now that I've done further research perhaps I should have considered the reverse recovery characteristics too.
...ultra-fast recovery diodes or silicon carbide Schottky Diodes with extreme low Qrr are needed for CCM mode.
But the Vishay datasheet doesn't comment on this at all so should I presume that this isn't a selling point for the SS36. Speed isn't mentioned in the headline "FEATURES". Looking on RS uk, RS3A is called "Fast" and mentions a test recovery time of 150ns (http://docs-europe.electrocomponents.com/webdocs/0dae/0900766b80dae6e2.pdf). Would RS3A be a better choice, or should I not assume it's any better than SS36?
Since the highside FET takes the bulk of the current perhaps I should choose a smaller device that suffers a higher voltage drop for the 500ns that it's needed, but has better reverse recovery.
Any advice appreciated. Robin
When designing the circuit I focused on the diode's voltage drop and choose a Vishay SS36 (http://www.vishay.com/docs/88751/ss32.pdf). But now that I've done further research perhaps I should have considered the reverse recovery characteristics too.
...ultra-fast recovery diodes or silicon carbide Schottky Diodes with extreme low Qrr are needed for CCM mode.
But the Vishay datasheet doesn't comment on this at all so should I presume that this isn't a selling point for the SS36. Speed isn't mentioned in the headline "FEATURES". Looking on RS uk, RS3A is called "Fast" and mentions a test recovery time of 150ns (http://docs-europe.electrocomponents.com/webdocs/0dae/0900766b80dae6e2.pdf). Would RS3A be a better choice, or should I not assume it's any better than SS36?
Since the highside FET takes the bulk of the current perhaps I should choose a smaller device that suffers a higher voltage drop for the 500ns that it's needed, but has better reverse recovery.
Any advice appreciated. Robin