RE46C190
DS22271A-page 28 2010 Microchip Technology Inc.
5.1.3 LOW BATTERY CHECK CURRENT
The Low Battery Check Current is the current required
for the low battery test. It includes both the loaded
(RLED on) and unloaded (RLED Off) tests. The boost
component of the loaded test represents the cost of
charging the boost capacitor to the higher voltage level.
This has a fixed cost for every loaded check, because
the capacitor is gradually discharged during
subsequent operations, and the energy is generally not
recovered. The other calculations are similar to those
shown in Equation 5-1. The unloaded test has a
minimal contribution because it involves only some
internal reference and comparator circuitry.
5.1.4 BATTERY LIFE
When estimating the battery life, several additional
factors must be considered. These include battery
resistance, battery self discharge rate, capacitor
leakages and the effect of the operating temperature
on all of these characteristics. Some number of false
alarms and user tests should also be included in any
calculation.
For ten year applications, a 3V spiral wound lithium
manganese dioxide battery with a laser seal is
recommended. These can be found with capacities of
1400 to 1600 mAh.
