Im working on a model rocket flight computer and i am trying to use a PMPB10XNX for a low side mosfet switch but it doesn't seem to work and i don't know why. Im using this schematic with Rin being 100 Ohms and Rgs being 10K.
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What is the ON/OFF Vds voltages ?
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Show us good images of your wiring.
Yea
sorry i forgot to mention i'm powering +vin with 3.3V from a pi pico.
Here is the wiring. I used a different symbol because the 10XNX didnt have one, they have the same pin out.
Usually a MOSFET that switches with logic level Voltage has an L in the name. Otherwise it needs 10+ V, as in 12V.
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The data sheet says it can be switched with a minimum of 1.5V.
Pretty small package - and "odd" pinout.
Is it for igniting a 'motor' ?
Yes.
- What are the ON/OFF Vds voltages for Vgs High/LOW?
- Show us good images of your wiring.
Minimum is 0.4V. My PCB design has way more stuff than just this so its hard to get a good picture of it. Here is the data sheet: https://assets.nexperia.com/documents/data-sheet/PMPB10XN.pdf
Oh so i might not even have the same component pinout?
You picked a good MOSFET that should work for you. R10 is on the wrong side of the 100 Ohm gate resistor, it is forming a voltage divider. R10 is there to turn the MOSFET off during reset and setup and hold it there until your code decides to turn it on. Use your volt meter, you should have over 3V on the gate. If not you have a broken wire or bad MOSFET.
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Haven't seen your layout.
Ok, thanks i will try that.
It was at about 3.3V
Then the source should be zero and the drain just about 0.02V (very low). If the drain is high, the source is 0 and the gate is 3+ you have a bad FET. If the source is above about 0,3V you have a bad connection. 100 Ohms should be just fine.
Ok, i will try swapping out the fets for new ones.
It works! Thats annoying all it was was a bad fet.
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Hi, @mrd_aerospace
What is the load?
With the load connected.
What is the supply for the load?
Use your volt meter, measure the voltage on the Drain of the MOSFET when the gate goes to 3V.
Use your volt meter, measure the voltage on the Source of the MOSFET when the gate goes to 3V.
Did you breadboard your project first to prove it works?
If you have a spare PCB, use your DMM to check each connection from terminal to MOSFET.
Thanks.. Tom... 
