Biasing Mosfet far below nominal Vdd

[Politecnico]

Hi guys

What happens if I bias a Mosfet far below the nominal Vdd? In case of Si2318CDS, nominal Vdd is 40V and I just need to bias it at Vdd~6V. Could there be some kind of malfunction?

Thanks a lot, in advance

 

[dick_freebird]

At the drain, no prob. But power MOSFETs (at least the
older, cheaper generations) want a large Vgs to fully drive
down the on-resistance (8V - 12V) and if you are trying
to drive a high current at 6V Vgs, you may find the FET
is more dissipative than you expect. A "logic level" FET
could be a better choice, if it meets the other constraints
(cost, tolerance to -too high- a gate voltage, etc.).

 

[Politecnico]

At the drain, no prob. But power MOSFETs (at least the
older, cheaper generations) want a large Vgs to fully drive
down the on-resistance (8V - 12V) and if you are trying
to drive a high current at 6V Vgs, you may find the FET
is more dissipative than you expect. A "logic level" FET
could be a better choice, if it meets the other constraints
(cost, tolerance to -too high- a gate voltage, etc.).

Thanks a lot for your kind reply.
Actually, Si2318 Datasheet says it could switch at 4.5V, as well 10V. Does it mean far from cost, ... there would be no critical problem of biasing the drain at 6V?

 

[crutschow]

The drain voltage specification is the maximum drain allowed voltage.
You can use any drain voltage less than than.