Data Sheet

AN1012 TIMEKEEPER products
Doc ID 6395 Rev 4 15/33
5.2.2 M48T08 and M48T18
The next TIMEKEEPER
®
to be released was the MK48T08/18 family, which has an 8K x 8
SRAM array. By using the more advanced 1.2 μm HCMOS3 process and refining the on-
board oscillator, STMicroelectronics was able to offer a nearly three-fold increase in battery
lifetime, even though the array size had increased by a factor of four. This product was later
converted to the 0.6 µm, double-level metal HCMOS4PZ process for 4T SRAM cells. The
battery was then upgraded to 120 mAh for the CAPHAT™ package revision (part numbers
M48T08/18), which provides a battery life of at least 10 years across the commercial
temperature range (0 °C to 70 °C, see Figure 7).
In the M48T08/18 datasheet, the battery lifetime (t
DR
, data retention time) has been
specified as 10 years or greater across the commercial temperature range (for a 0% V
CC
duty cycle).
Figure 7. M48T08/18 data retention lifetime vs. temperature (120 mAh, 100% battery
backup)