0

I would like to know if there is a limit on voltage between gate and drain, What happen if the gate voltage is over drain voltage. I looked at datasheets but won't find anything.

Thanks

shangaoren filehunter
  • 1
  • 2
  • 2
  • 2
    Look harder? Preferably at the section "Absolute maximum ratings". You might need to use some math. – PlasmaHH Apr 24 '17 at 08:55
  • absolute maximum rating give me VGS and VDS but i can't see anything to calculate VGD. By exemple set my gate on 12V (maximum rating in that case) and Drain is at 3.3V will it have current flowing from gate to drain ? – shangaoren filehunter Apr 24 '17 at 09:34
  • The Vgs range will be specified, as will the Vds range. They're both referenced to source 's' so you can calculate Vdg(max) from these. – TonyM Apr 24 '17 at 10:35

1 Answers1

1

The limit is the total of Vgs(max) and Vds(max), added with appropriate signs, unless otherwise specified, as with this 2N7000 datasheet.

enter image description here

You cannot just connect a voltage source between drain and gate and crank it up to 800V or whatever the MOSFET is rated for- you must constrain the gate-source voltage to remain within the acceptable range (the example above indicates a resistor so Vgs~= 0V).

Driving a MOSFET 'on' means the magnitude of the drain-gate voltage is less than the drain-source voltage. It can be more if you drive the gate 'off' - in the 2N7000 example you might have -15V on the gate, in which case the drain voltage should be less than 45V.

Spehro Pefhany
  • 376,485
  • 21
  • 320
  • 842