Datasheet

Ideally, this backpack is for use with the 3.3V Pro Trinket, so that the battery voltage (3.7V-
4.2V) will get regulated down to 3.3V on the Pro Trinket board. However, many times, you
can run a 5V Pro Trinket + accessories off of the ~4V from the LiPoly battery with no
problem. (Technically its overclocking but we've never seen that affect the Pro Trinket itself,
AVRs are happy to overclock without complaint).
© Adafruit Industries
https://learn.adafruit.com/adafruit-pro-trinket-lipoly-slash-liion-
backpack
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