identifying suitable FET's


i have quick question fet's.  i'll talking p-channel here.

a short while ago told me on datasheet vg when quoting rds(on) identifies if logic level fet.  i bought , using without problems fqp27p06 (p channel fet).  in vg quoted -10v rds(on) of 0.07ohm.

i thought vg quoted @ rds(on) have -5v or particular fet ok use @ logic level because of vth (-2v -4v) , low rds(on).  meaning @ logic level rds(on) higher quoted in datasheet because low begin fet won't heat as other fet's 0.4 ohm resistance @ vg -10v being used @ logic level , therefore safe use.

i guess sum i'm asking is.  can p channel fet called logic level , used arduino if vth -2v -4v , rds(on) still low enough @ logic level compared rds(on) @ -10v quoted in datasheet?

errr...maybe.

you not have logic-level fet. vgs rating @ 2v-4v says if need supply 250ua through fet (from source drain) won't need more -4v on gate-to-source junction. beyond that, don't tell until have -10v gate-to-source, @ point source 13.5a , have on-resistance of 0.07 ohms.

in between...you don't know (well, can predict , model, there no guarantees). reason using "without problems" because not source lot of current through fet, -5v gate voltage enough job, doubt fet's on resistance (if measure it) near 0.07 ohms.

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