The circuit I plan to use for a push button to turn on my (Itsy Bitsy M0) currently includes an NDP6020 N-Channel mosfet.
It will be switching a 9v battery circuit that feeds a buck converter to bring the voltage down to 5v to power the Itsy Bitsy.
I want to use an SMT version, but the NDB6020 is listed as obsolete.
Can anyone tell me what a common SMT replacement for the NDP6020 would be that isn't obsolete? I'm afraid my electronics knowledge isn't good enough to handle all the specifications on the data sheets.
IF something is listed as being obsolete does NOT mean it is not available. How many are you intending to buy?
This is a prototype. I only need one or two right now, but if it all works it may become a mass production item. It doesn't make sense - to me, anyway - to design and test something knowing that I may have to change and retest it.
You are asking for a SMT version of a device that has a 60 watt dissipation rating. That is just not ever going to happen.
We need to see how the MOSFET is being used before we can recommend an alternative.
Given that you don't know enough electronics to make sense of the data sheets, for a mass produced item, consider hiring help from someone who does understand them. This forum has a Jobs and Paid Consultancy section.
Switching a 9V battery? Practically any FET will do. I assume it needs to be logic level according to your application?
The biggest problem will be finding one that you can actually buy! I just looked up availability of an IRLML2502 (it's overkill for this, but I had a few in a drawer and they're cheap) and pretty much no one has any in stock. These supply chain problems are killing us!
Um err.
For a 'mass production item' I would suggest that a public forum of volunteers is not the best place to get advice at all.
Yeah, but the advice is free 
For sure.
The Internet is full of free 'advice'.
This is the basic circuit. 9v power is supplied across JP2. The Microcontroller is connected to a buck converter (to bring the voltage down to 5v) which is connected across JP1-2 and JP1-1. Power is initiated using the pushbutton switch at JP1-4, and held on by a signal from the microcontroller applied to JP1-3.
Screenshot Powerboard Schematic.pdf (86.3 KB)
You say N channel and picked a P channel.
What’s up here, we really need to be accurate here 
.
Just went by Digikey's list for the device. They showed no other package.
OP said it's for a 9V battery, so I'm guessing not a whole lot.
Good catch - yes it is indeed a P channel.
Current draw is less than 1 Amp.
This is a long long way from being a mass production item. It is in the realm of a prototype for something that may work well, poorly, or may not work at all.
My point was that I really don't like to design something using parts that I know up front are obsolete.
Also listed as obsolete by Digikey ...
Okay then, use an AO4419.
I’ve use both with great success.