Velleman DCA75 - Manual (Page 22)

Atlas DCA Pro User Guide December 2012 – Rev 1
Page 22
N-Ch Depletion
mode MOSFET
Red-S Green-G Blue-D
Gate threshold
VGS(on)=-2.918V
at ID=5.00mA
Depletion Mode MOSFETs
The fairly rare Depletion Mode MOSFET is very similar to the
conventional Junction FET (JFET) except that the gate
terminal is insulated from the other two terminals. The input
resistance of these devices can typically be greater than
1000MΩ for negative and positive gate-source voltages.
Depletion
Mode devices are
characterised by the gate-source
voltage required to control the drain-
source current.
Modern Depletion Mode devices are
generally only available in N-Channel
varieties and will conduct some current
between its drain and source terminals even with a zero voltage applied across
the gate and the source. The device can only be turned completely off by taking
its gate significantly more negative than its source terminal, say –5V. It is this
characteristic that makes them so similar to conventional JFETs.
VGS
Depletion mode
MOSFET
Enhancement mode
MOSFET
IDS
5.0mA