My switching will be around 2-3A and the output voltage will be 150V max, 100khz.

Im looking on digikey and I asked AI but I dont really know which ones are the good ones that are commonly used.

 

you would want part that hand handle a but higher voltage (200VDC+), also higher current rating for thermal limit..s. and of course low Total Gate Charge (Qg) and low Input Capacitance (Ciss) to reduce switching losses. one of very common parts is IRF640N but there are many alternatives.

 

not sure what package you are looking for. for THT parts maybe IRFP4568... if SMD, i 'd go with something like FDMS86150

 

If you get too small a device, then Rds(on) is high and you get conduction losses.
If you get too large a device, then it does not switch as fast and you get switching losses.
(You can make it switch faster, but that needs a larger gate driver(
Somewhere in the middle is the device that gives the lowest overall losses.

 

If you get too small a device, then Rds(on) is high and you get conduction losses.
If you get too large a device, then it does not switch as fast and you get switching losses.
(You can make it switch faster, but that needs a larger gate driver(
Somewhere in the middle is the device that gives the lowest overall losses.

what you think about this one

IRF640N

 

0.18Ω Rds(on) gives 1.62W dissipation at 3A. I suspect it's bigger than it needs to be. I bet IRF630 might do the job.
But they are both old devices (introduced in 1979). You could probably get a more modern device with Rds(on) that low with lower gate charge.