Imho only the FET qualifies (wow at what price) for a 3A supply, and I say
that without looking at max. dissipation which you did not list.
Transistors in TO92 tend to go bad when dissipating more than 0.5W or so
(even that is a lot).  According to your efficiency figures a 3A/5V supply
will have 15W out and burn 1.5W on the circuit (assuming efficiency stays
as good with the higher current, which I doubt). Even if only 1/3 goes to
the TO92 it will try to melt.

On Fri, 27 Sep 2002, Roman Black wrote:
*>
*>ZTX13P40DE6, PNP, 40v, 3A av, 10A pk,
*>25mV Vce @ 0.1A, beta=300 (SMT SuperSOT4)
*>$1.71 (100 0.88)
*>
*>ZTX951, PNP, 60v, 4A av, 15A pk,
*>0.3V Vce @ 4A, beta=100 (TO92 flat)
*>$2.57 (100 1.32)
*>
*>ZTX953, PNP, 100v, 3.5A av, 10A pk,
*>0.33V Vce @ 3.5A, beta=100 (TO92 flat)
*>$2.75 (100 1.51)
*>
*>FDR858P, PFET, 30v, 8A,
*>Rds = 19mohm 0.057V Vce @ 3A, (SMT SuperSOT8)
*>$3.38 (100 1.80)

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