MOSFET Selection Help

Need help selecting some MOSFET's - sorry lost my notes but - for standard 5v Arduino - mostly switching small loads - LED's etc.

Both N & P Channel, 60v seems to be a standard max voltage, 200ma should be enough, TO-92 case, looks like a pile will be needed, so want to stay away from the TO-220 package and reduce the cost and size. General use.

Thanks for your help

TO-92 is rare for MOSFETs, it's considered an old style package, and it's rarely if at all used for new designs. Most are SMD packages (which are cheaper in both construction and manufacturing than TO-92), or TO-220 as it makes it so easy to attach to a heat sink.

The 2N7000 is one common option. Here an overview of other options.

I want to do through hole, I have a few TO-220's but don't need the higher current capacity. I don't want SMD as I plan on using solder perf. boards and I have never soldered SMD and would need carriers and that would make the design more complex

Thanks for the 2N7000 & Link - parts selection is very painful for me.

SMD MOSFETs are easy to solder on solderable perf PCB.


P Channel

  • FDN340P
  • AO3401

N Channel

  • IRLML2502
  • Si2302DS

Of course there are hundreds of BJT TO-92s

I've been researching the same issue, and have found that none of the mosfets available in TO92 have low RDSon values. You're looking at about 2 ohms or more, whereas the SOT23 mosfets can be down to 0.1 ohms or less. If you are switching low currents, that's not a problem, but if you're switching 200 mA with a mosfet like the 2N7000 with 4 ohms of RDSon, you'll have a voltage drop of 0.8V across the mosfet, which is a lot. And possibly a lot of heat.

But I need through-hole too for breadboard work, so I've ordered some of the SOT23-to-SIP adapter boards from the Far East (10 for a dollar). I think if I use right-angle header pins, or just use wires and bend them 90 degrees, the adapter board will be standing straight up on edge, and not take up much more room than a TO92. Both will use three adjacent holes in the breadboard.

Right now I need P-channel, and have settled on the IRLML6401 (12V) or 6402 (20V), but there are lots of choices such as those larryd has listed.

I just wish there was an easy way to solder the SOT23s to the adapter boards. I think maybe superglue them in place first. Or maybe pre-blob some solder on the pads, and get out my hotplate. :slight_smile:

SOT-23 is limited to 20V VDS. Enough for many projects but not for everything. 100 mΩ is quite high an on resistance :slight_smile: You can easily find parts with 10-20mΩ at VGS=3.3V.

The BSS138 and BSS84 are also very nice parts, perfect for small signals (the BSS138 is commonly used in level shifters). Very low gate charge, low threshold voltage. Fairly high on resistance but that doesn’t matter for signals, the low gate charge is more important.

Those SIP boards give the same pinout but are a bit more bulky than the TO-220 package… which OP found too bulky (even though they barely take more space than a TO-92).

“ I just wish there was an easy way to solder the SOT23s to the adapter boards.”

Avoid glue.

Make one of these:

See post #463 and #475

Thanks everyone for the tips and how to link and part numbers