p-channel mosfet heat dissipation


Joined Apr 28, 2019
Hello crookedspoon & Audioguru
Just to be clear, running the spice model for the IFR4905 in the DC analysis mode, returns the following result:
For a drain current of 1.47 Amps the gate to drain voltage needs to be -3.92 volts, of course this isn't set in stone, and will varies from device to device and temperature.
I’ve included the circuit for clarity.

Regards GaryW.


Joined Mar 26, 2017
Where did you get that odd idea?
There's no such thing as a "linear one".
All MOSFETs can (and are) used as DC switches.
If you look at fig.8 from the data sheet you would notice that the curves stop for signal of 1 (one) pulse 10ms wide. There are no curves for dc signal. Also Rds on is defined ONLY for pulses of 300us and duty cycle of less than 2% (note 4) which is far away than a dc signal. Search linear MOS, an N-type, from IXYS, for example IXTK90N25L2. which is specifically built for working in dc signals.