Operating conditions: 10 to 30 volts DC, either polarity.
I'm needing to rectify DC power because the polarity is undetermined. The voltage is 10 to 30 volts and the current up to 6 amps. Since at 6 amps, the conducting diodes would dissipate like 4 1/2 watts each, I wanted to do better for this SMALL device. (They dissipate more heat than the H bridge motor driver.)
So I went looking for mosfets to make a bridge. Cheap ones have like a +- 20v Gate-Source spec, so I used a resistor divider.
Theory of Op: A resistor divider gives me V/2, or between 5 and 15 volts.
V/2 applied to the gate of the PFet on the + side turns it on, connecting the output to the + side. Since V/2 is "above" the - side, that PFet is turned off.
V/2 applied to the gate of the NFet on the - side turns it on, connecting the output to the - side. Since V/2 is "below" the + side, that NFet is turned off.
Does anybody see sparks, smoke or melted plastic trains from this arrangement?
Oh. Yes. The PFet is FDS4435BZ
The NFet is PMN25EN
Only because they're small, rated and available at reasonable cost.