Just one caveat to the FETs, that property is only guaranteed in the full-on (a.k.a ohmic) region. If the FET is partially on (or in the linear region), then the behavior is usually the opposite and the hotter FET will take more of the current. This can even be a problem in switching applications because the FETs spend some of their time in the partially ON state as the switch from off to on and on to off. If a significant fraction of the overall power dissipation comes from these switching transients (and it often does), then you can still encounter unequal current sharing with parallel FETs in a switching application. Also, temperature affects the voltage at which the FETs turn on and it may be that the hotter one will turn on sooner and take the entire switching transient. Sean On Wed, Oct 6, 2010 at 6:21 PM, ivp wrote: >> However, you can't just put two diodes in parallel and add their >> current ratings. =A0This is because they won't share the current equally > > I see that now. The circuit which made me pose the original question > uses switching FETs in parallel, with individual gate resistors. AIUI > FETS have a negative temperature coefficient, ie local hotspots on the > die increase in resistance, thereby causing a temperature decrease, so > there is no thermal runaway. The suggested 2 Schottky =3D 1 UF sub > does not mention load-sharing resistors, as you'd find on paralleled > power bipolar transistors for example, which would prevent current > hogging > > Thanks for everyone's input > > Joe > > * > * > ********** > Quality PIC programmers > http://www.embedinc.com/products/index.htm > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .