Arduino Nano Digital Output fails when 6 pins are used

***Edit I attached the images
I'm currently working on a Brushless DC Motor Controller with Arduino but I have a problem with a Digital Output. The problem is the following:

I have 6 Digital Outputs to control an Inverter(H Bridge with 3 Arms)


(1,3,5) PWM Outputs for the High Side Mosfets and (2,4,6) Outputs for the Low Side Mosfets.


I was measuring the voltages for the High Side Transistor Outputs Gates and they are fine when only they 3 are connected to the board.

If I connect the 6 Outputs to the board, one fails, one from the High Side.

For this Test I have no Mosfets connected on the Protoboard

By connect to the Board I mean From Arduino Nano to the Protoboard. And the one that fails is the Transistor at the second image for G5. I will buy another MC34151, but this schematic should work, right?

G1 and G3, measure 11.5V when " input off" and around 7V when "input PWM at ~50%" also G5 measures that when D5, D6 and D7 are not connected to the protoboard.

If I connect D5 to the protoboard everything is still Ok, If i connect D5 and D6, G5 Measures 10, then 7 then 4 then 0, Something like that. If I connect D5, D6 and D7, G5 measures roughly 1.5V.

Any Ideas?

Thank you and sorry for the long post.


Please read the "How to post" sticky, so we can actually see your diagram and code.

Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.,148850.0.html .

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks.. Tom... :slight_smile:

Thank you for the reply, I read the Tutorial and I attached the images instead. Hope it works.




When taking photos, please do so in daylight - outside; but not in full sun. Unless you have a proper professional studio. :astonished:

The gate of an N-channel fet needs to be ~10volt higher than it's source for the fet to fully conduct.

Now look at the top three fets in your first diagram.
Are you able to drive the gates 10volt higher than their sources (= drains = motor supply when conducting).

Sorry I forgot to mention I'm using P-Channel Mosfets for the High Side of the Inverter, I have a ~12v driver that outputs 0 in order to make the mosfet conduct current, and 12 to be open.