Data Sheet

TIMEKEEPER products AN1012
14/33 Doc ID 6395 Rev 4
5.2 TIMEKEEPER
®
evolution
TIMEKEEPER products have seen a continuous evolutionary cycle since their initial market
introduction in the 1990s.
5.2.1 M48T02 and M48T12
The first TIMEKEEPER products released were the MK48T02 and MK48T12 which offered
2K x 8 RAM and employed the STMicroelectronics 2.0 μm Spectrum™ CMOS technology.
When released, these products included a BR1225 lithium cell with a specified 39 mAh
capacity. This combination offered the user approximately 3.5 years of continuous battery
backup life. Since that time, the devices have been moved to the 4T cell technology
(HCMOS4PZ) and a CAPHAT™ package revision which includes a larger capacity lithium
cell (120 mAh BR1632) capacity, and new part numbers (M48T02/12). These changes
increased the expected battery life to 19 years at 60°C.
Figure 6 shows expected battery lifetime versus temperature with 100% battery backup. The
data shows that by operating the devices at various temperatures, designers can expect a
battery life approaching 20 years under most conditions.
Figure 6. M48T02/12 data retention lifetime vs. temperature (120 mAh, 100% battery
backup)