I am working with the following product: Lilypad Mini Protosnap https://www.sparkfun.com/products/14063
and have a few questions:
There are 2 parallel LED circuits on the board, each with 2 White Micro Leds which have a 150 ohm resistor per LED.
I want to know how this board works, since voltage drop for a white LED is 3.3-4 and the source voltage is only 3 V for the coincell battery [CR2032].
The led's work, and I don't understand how this is?
Secondly, how would I calculate if the I/O pin can take additional micro LEDS?... So far i know that each pin has a maximum current of 40mA and each LED has a max current of 20mA.
This whole circuit feels problematic and would be happy to have some clarification, should anyone be able to assist?