Datasheet

M48T08, M48T08Y, M48T18 Description
Doc ID 2411 Rev 11 5/31
1 Description
The M48T08/18/08Y TIMEKEEPER
®
RAM is an 8 K x 8 non-volatile static RAM and real-
time clock which is pin and function compatible with the DS1643. The monolithic chip is
available in two special packages to provide a highly integrated battery-backed memory and
real-time clock solution.
The M48T08/18/08Y is a non-volatile pin and function equivalent to any JEDEC standard
8 K x 8 SRAM. It also easily fits into many ROM, EPROM, and EEPROM sockets, providing
the non-volatility of PROMs without any requirement for special WRITE timing or limitations
on the number of WRITEs that can be performed.
The 28-pin, 600 mil DIP CAPHAT™ houses the M48T08/18/08Y silicon with a quartz crystal
and a long-life lithium button cell in a single package.
The 28-pin, 330 mil SOIC provides sockets with gold-plated contacts at both ends for direct
connection to a separate SNAPHAT
®
housing containing the battery and crystal. The unique
design allows the SNAPHAT
®
battery package to be mounted on top of the SOIC package
after the completion of the surface mount process. Insertion of the SNAPHAT
®
housing after
reflow prevents potential battery and crystal damage due to the high temperatures required
for device surface-mounting. The SNAPHAT
®
housing is keyed to prevent reverse insertion.
The SOIC and battery/crystal packages are shipped separately in plastic anti-static tubes or
in tape & reel form. For the 28-lead SOIC, the battery/crystal package (e.g., SNAPHAT
®
)
part number is “M4T28-BR12SH” or “M4T32-BR12SH”.
Figure 1. Logic diagram
AI01020
13
A0-A12
W
DQ0-DQ7
V
CC
M48T08
M48T08Y
M48T18
G
E2
V
SS
8
E1 INT