WP 34S Power Requirements Message #1 Posted by Marcus von Cube, Germany on 26 July 2011, 6:14 a.m.
After having worked on the power saving code recently, I just made new measurements of the power drain of my lab 20b. Here are the results (all values in mA):
State FAST SLOW
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off 0 No display
sleep 0.15 LCD running
idle 0.82 LBL B; PSE 99; GTO B
debug 1.66 ON+D
serial 6.60 3.15 without the cable connected
run 20.5 8.99 LBL A; GTO A
SLOW can be set with the SLOW command or ON+1 (the latter behaving exactly like a low power situation). The SLOW command survives a power cycle, ON+1 is transient.
I'll probably reduce speed to the slow mode (20 MHz) for serial I/O if it proves to be reliable enough, just to save some power during the "Wait..." phase. The cable furnished by HP draws about 1.5 mA alone, even while the calculator is turned off!
I'd love to see measurements by people with better lab equipment then mine. How is the original firmware by HP (20b and 30b) performing in a similar setup? I'm looking forward to your feedback.
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