Battery monitoring circuit not working

Thread Starter

irmanao

Joined Apr 29, 2017
87
I tried this battery monitoring circuit (https://community.particle.io/t/mea...photon-is-connected-to-4-aa-batteries/18486/3) but it's not working as i thought it would. Battery is 3.3-4V.
My circuit is the same but without the LED. The p-channel mosfet never seems to turn on because the first mosfet is not either?(p-channel's gate is always 3.3V when i bring the trigger line high(3.3V) or low)
Am i missing something?
thanks
 

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Thread Starter

irmanao

Joined Apr 29, 2017
87
I mentioned it, it's 3.3V from a microcontroller. Also p-channel mosfet is PMV160UP.

thanks
 
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ericgibbs

Joined Jan 29, 2010
13,197
OK,
That looks OK.
So it is either a wiring error or a faulty NMOS.
If you can post a photo of the PCB so that we can check it.
E
 

Thread Starter

irmanao

Joined Apr 29, 2017
87
For the n-channel, pins 1,2,5 and 6 are connected in the datasheet internally and when i test it with multimeter's continuation tester it's ok.
When i apply voltage to the circuit and measure voltage in pin 1 however, the voltage is 3.3 but the voltage on the rest of the drain pins is 0.
 

Thread Starter

irmanao

Joined Apr 29, 2017
87
I will try.
Also, the drain pins are connected internally (checked) and R20 is connected to drain (pin1) (checked) but not the rest of drain pins!!
how?..

Update: Ok never mind i'm an idiot... bad connection on the board (pin1 was not connected to the pcb). I checked it before but obviously not thoroughly. Sorry for wasting everybody's time and thanks a lot for the help. Next time i'll be more thorough before posting but this time i am in a hurry trying to make this work. Sorry again.
 
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