> Doesn't seem that you gain or loose anything here - assuming the > switching time is not affected.
The FET helps because there's an ohmic loss across the diode on the order of Io*Vf when the switcher is in the off state. The FET has a lower Von (Vf) than the diode, which reduces this particular loss. You still need the diode, though, in case there's current during the transitions. > The trick is to make sure the lead + track inductance to each cap > looks similar (else the nearest one to the switch will fail first). The board was limited by physical spaces, so I just used really big tracks. Plus I put a bypass cap right at the switcher. Some switchers have EMI suggestions for input, too. > 105 degree rated caps are often worse on ESR, so in some > applications will run hotter. I read somewhere that its best to use > 85 degree caps unless the heat is imposed _on_ the caps (rather than > from internal dissipation). And choosing caps with higher voltage ratings helps them last longer, too. _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user