Under Voltage Protection for LiPo Battery
There's battery monitoring, and battery protection.  They're two different things, and different design considerations apply to each.  Sending a signal to a microcontroller is a good design for monitoring -- you can alarm and tell the user their battery is low.

But generating a digital signal isn't stopping discharge, so it doesn't provide any protection to the cells.  The only way you can read your digital signal is by powering the microcontroller... which continues to drain and damage the battery.