Push button power circuit for Arduino... trying to modify it for 12V input

Thread Starter


Joined Oct 18, 2013
Hi All,

I found this circuit that allows for the use of a momentary push button to power on an arduino and then the arduino provides the "hold" signal to continue the power latching on.


I have an application where I will have a ~12.6V input power from (3) 18650 batteries in series (when fully charged). Unfortunately there are a few components not rated for this type of input voltage (max 8V). I have tried to find equivalent components with a higher max input voltage... so I replaced the TPS27081A with a Si3865DDV... same foot print and pinout... I also replaced the P channel mosfet FDV302P with BSS84 so that the max GS voltage is above 12V.

I think that should do it... however, based on the circuit in the link I provided it would seem that when the pushbutton is pressed and the p-channel mosfet gate is pulled low, the "BTN" line that would go to the Arduino would see my battery voltage of ~12V ? It would also seem that pin 5 (ON/OFF) of the TPS27081A (or in my case the Si3865DDV) would also see the 12V ? The Arduino can only handle 5V input and the Si3865DDV can handle up to 8V on pin 5...

Am I understanding this correctly? I don't want to fry either of them...

If I put a resistor ahead of the supply pin on the P channel mosfet, would it work with R2 to create a voltage divider? I'm just not sure what effect R1, the diode, and R3 would have on trying to create this voltage divider to get down to 5V

If anyone can help me out with these few details I would really appreciate it!

Thank you