In article ,
Jim Adney wrote:
On 8 Jun 2004 10:37:53 -0700 Winfield Hill
wrote:

If that's true, the FET should be paralleled with a Schottky diode.
For that matter, did anyone suggest he simply use Schottky diodes?

I may be wrong, but I think both you guys have missed the point of his
question.

You may be assuming incorrectly that we are aiming at his point. We are
talking about using MOSFETs as recifiers and one strange case I had some
years back.

He stated that he is already using Schottkys. He wants
something with less voltage drop.

If you use a MOSFET as a rectifier, you get less drop than a Schottky.
The sticking point is that until you've rectified some power you don't
have the voltage needed to make the gate drive for the MOSFET. We solve
this by putting the Schottky in parallel with the MOSFET. Initially, the
Schottky does the work and gets the voltage part way up. Once enough
voltage has been made to run it, the MOSFET takes over the work.

[....]
forward voltage drop. I suspect that he has no knowledge of the
reverse intrinsic diode (which makes this approach a complete looser)

No, all you have to do is flip the Source and Drain legs of the MOSFET and
the idea works just fine, assuming the gate drive is there as needed.


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