FRAM71B
User’s Manual
FRAM71B 1.00
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©Hans Brueggemann, 2016
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Current
Consumption
In order to conserve battery energy, FRAM71B sends its FRAM chip routinely into deep sleep
mode every time the HP-71B goes into SHUTDOWN. However, FRAM71B’s power supplies
will stay fully on even when the calculator is OFF. This is required to allow for immediate
access to SYSRAM when the calculator is switched ON. The average current consumption of
a base system plus installed FRAM71B-1024 is approx. 46 µA during OFF. Hence, with a fresh
set of high- quality batteries installed, your HP-71B will sustain approx. 54000 hours (> 6
years) in OFF- state before waking up with a "MEMORY LOST” message.
Picture 10: FRAM71B current consumption in various operating modes.
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