Teensy 3.2: 3.3V regulated power source (bypassing onboard reg)?

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XFer

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Hi everyone!

I'm new to the game: longtime Arduino user, just discovered these Teensy gems! :)

I have a project where everything is running at 3.3V (power, signals, etc.) and I already have a 3.3V regulator to power everything.

The Teensy 3.2 I'll use won't have to directly power anything.

I know that the Teensy is usually powered by USB (regulated 5V) or unregulated external power source.

I'm wondering if I could power the Teensy 3.2 directly off my 3.3V regulator, to simplify the design (no need for a 3.3V->5V stepup) and hopefully save power (battery-operated device).

This, of course, after having uploaded my sketch via USB; I won't need USB anymore after that.

Thank you very much for any hint!

Fernando
 
Yes, you can add power/ground to the 3.3v pin from regulated sources. However, you don't want to have another power source to VIN/VUSB while you are feeding regulated power to the 3.3v rail.

You might want to cut the solder jumper between VIN/VUSB underneath the teensy if you want to program the teensy via USB but not take the power from the USB connection. I don't recall if it works for power to the 3.3v rail (normally I see people posting about powering the VIN rail). Here is an old posting that discusses it: https://forum.pjrc.com/threads/1922...ng-VIN-from-VUSB-Teensy-3-0?p=44024#post44024
 
You want GND (not AGND) which is the first pin on the right side as the USB connector faces down, and 3.3v which is the third pin on the left side. Or if you want adjacent pins, there is the 3.3v and GND pins on the back of the Teensy.
 
Thank for the clarification Michael. :)

These ones:

teensy32b_3Vpins.jpg
 
Yes, those are the correct pins. You can also use the 'V' and 'G' pins on the very back. Or if you want to solder, there are 3v and gnd pads on the bottom (between pins 19 and 6).
 
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