I have an LED project for which i'm using a 9v power supply. For part of the project I'm using an off the shelf LED driver that is compatible with 9v however I have one LED component that I want to drive with the attiny85 (random blinking pattern), which is not compatible with 9v.
Does it make any sense to power the attiny85 separately with say a 3v coin cell, while allowing my LEDs to draw from 9v? The attiny85 would only be tripping transistors. I assume the attiny85 itself doesn't consume much power so hopefully I wouldn't be changing out the coin cell too often.
I have a couple 5v buck converters on hand but they take up more space than a coin cell would.
P.S. It's a Guy Manuel Daft Punk Helmet.