How does the rated on resistance of an N-FET differ for IDS < 0?

[Michael]

Hi there - in FET datasheets they always give lots of nice VDS vs IDS
charts and so on, but always for positive VDS and positive IDS. They
also will give limited specs for the body diode. But what if VGS > 0
and VDS < 0? My undertanding is that a FET can pass current in the
reverse direction nearly as well as in the forward direction - but is
that true? I can't find anything to back that up in any FET
datasheets.

If it matters, this is the FET I'm most interested in the reverse
current characteristics of: http://www.irf.com/product-info/datasheets/data/irlr8715cpbf.pdf

Thanks!

-Michael

 

[Tom Bruhns]

Hi there - in FET datasheets they always give lots of nice VDS vs IDS
charts and so on, but always for positive VDS and positive IDS. They
also will give limited specs for the body diode. But what if VGS > 0
and VDS < 0? My undertanding is that a FET can pass current in the
reverse direction nearly as well as in the forward direction - but is
that true? I can't find anything to back that up in any FET
datasheets.

If it matters, this is the FET I'm most interested in the reverse
current characteristics of:http://www.irf.com/product-info/datasheets/data/irlr8715cpbf.pdf

Thanks!

-Michael

Expect the resistance to be nearly constant at +/- a diode drop from
VDS=0, actually decreasing slightly as the voltage becomes more
negative, and eventually of course you get into the diode region and
it's the diode that offers the bulk of the conduction at that point.

Cheers,
Tom

 

[Michael]

Expect the resistance to be nearly constant at +/- a diode drop from
VDS=0, actually decreasing slightly as the voltage becomes more
negative, and eventually of course you get into the diode region and
it's the diode that offers the bulk of the conduction at that point.

Cheers,
Tom

Hi Tom - that answers my question perfectly. Thanks!

-Michael