Ultra Low Power display counter

This is a response video to Dave at EEVBlog's video here    • EEVblog #1242 - Memory LCD+Supercaps+Low P...   showing how to drive a 7 segment LCD display directly with an MCU in about 800nA: that's 14 years on a CR2016 button cell, 31 years on a CR2032, or 350 years with a pair of AA cells. Good luck with the cells not leaking or self discharging before then.

PIC is PIC16LF1904, $1.15 in 1ku.
Display is DE 117-RS-20/7.5, around $1.40 in 1ku

Base current with LCD peripheral running but all segments off is 410nA measured on a Keithley 238 SMU, so better than the Brymen BM869s meter I show in the video.

Each turned on segment adds about 13nA with this display.

When soldering any ultra low power stuff, make sure that you properly clean the boards afterwards: flux contaminants and alcohol cleaners typically contain some ionic content so will conduct and give inconsistent and unexpectedly high current results.

I strongly recommend using an ultrasonic cleaner for ten minutes with warmed appropriate cleaning solution, followed by a couple of thorough rinses in distilled water, then allow to fully dry. Drying can be speeded up by baking, using a preheater or hot air soldering iron on low temperature.