Unicorn Hat HD Power Question


#1

Hello,

Not sure if this is the right forum. I have a quick question about the Unicorn Hat HD. There’s no schematic or anything for it otherwise I’d probably know the answer.

For the 3.3V and 5V power input rails - I assume those power the ARM MCU and LED drivers respectively?

I ask because I am wondering what the “safe” voltage range is for the 5V. I wrote a library to make it work with my Adafruit Feather NRF52 (code is on github) and I’m trying to reduce the amount of components in my project.

It seems to work fine with the 5V connected to the battery pin (which is a direct feed from the 3.7v Lithium battery) during my unscientific test of letting it sit there while I was working on other stuff for several hours, but I’d like to avoid potential problems long term.


#2

You’re quite correct! The 5V powers the LEDs, so if you run them at a lower voltage, e.g. 3.6V (which may drop as the battery runs low), then your LEDs will be less bright and the red element of each LED will dominate the other two (because of the differing forward voltage of the LED elements).


#3

That’s what I needed to know. Thanks!