M48Z09 Ver la hoja de datos (PDF) - STMicroelectronics
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M48Z09 Datasheet PDF : 13 Pages
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M48Z09, M48Z19
Calculating Storage Life
The following formula can be used to predict stor-
age life:
1
{[(TA1/TT)/SL1]+[(TA2/TT)/SL2]+...+[(TAN/TT)/SLN]}
where,
– TA1, TA2, TAN = time at ambient temperature
1, 2, etc.
– TT = total time = TA1+TA2+...+TAN
– SL1, SL2, SLN = storage life at temperature 1,
2, etc.
For example an M48Z09,19 is exposed to tempera-
tures of 55°C or less for 8322 hrs/yr, and tempera-
tures greater than 60°C but less than 70°C for the
remaining 438 hrs/yr. Reading predicted t1% values
from Figure 9,
– SL1 ≅ 200 yrs, SL2 = 28 yrs
– TT = 8760 hrs/yr
– TA1 = 8322 hrs/yr, TA2 = 438 hrs/yr
Predicted storage life ≥
1
{[(8322/8760)/200]+[(431/8760)/28]}
or 154 years.
As can be seen from these calculations and the
results, the expected life time of the M48Z09, 19
should exceed most system requirements.
Estimated System Life
Since either storage life or capacity consumption
can end the battery’s life, the system life is marked
by which ever occurs first.
Reference for System Life
Each M48Z09,19 is marked with a nine digit manu-
facturing date code in the form of H99XXYYZZ. For
example, H995B9431 is:
H = fabricated in Carrollton, TX
9 = assembled in Muar, Malaysia,
9 = tested in Muar, Malaysia,
5B = lot designator,
9431 = assembled in the year 1994, work week 31.
Figure 9. Predicted Battery Storage Life versus Temperature
50
40
30
t1%
20
AI01399
t50% (AVERAGE)
10
8
6
5
4
3
2
1
20
30
40
50
60
70
80
90
TEMPERATURE (Degrees Celsius)
10/13
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