DM42 News

[brouhaha]

(03-10-2017 09:11 PM)Guenter Schink Wrote:  It's not eInk but low power transflective memory LCD. That is 50 µW consumption for static display.

50 µW for the display, plus power for a boost regulator to step the battery voltage up to the 5V needed by the display. Even the most efficient available boost regulators for that purpose consume another 50 µW or more. In the calculator prototypes Richard Ottosen and I have shown at the HHC Conferences, which run Free42 w/ display patches using that same LCD, when the calculator is turned off we actually remove power from the display and the boost converter, so that the display power consumption is 0 µW rather than around 100 µW.

We were running from CR2032 coin cells, so an extra 100 uW power dissipation in the off state would have a not completely insignificant effect on the battery life. Usable CR2032 capacity is somewhere around 500 mWh. (Capacity varies considerably by brand; no-name or off-brand batteries are often far lower).