M48T35 M48T35Y
Summary description
1
Summary description
®
The M48T35/Y TIMEKEEPER RAM is a 32Kb x 8 non-volatile static RAM and real time
clock. The monolithic chip is available in two special packages to provide a highly integrated
battery backed-up memory and real time clock solution.
The M48T35/Y is a non-volatile pin and function equivalent to any JEDEC standard 32Kb 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, 600mil DIP CAPHAT houses the M48T35/Y silicon with a quartz crystal and a
long life lithium button cell in a single package.
The 28-pin, 330mil 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” (see Table 18 on page 27).
Figure 1.
Logic diagram
V
CC
15
8
A0-A14
DQ0-DQ7
W
E
M48T35
M48T35Y
G
V
SS
AI01620B
5/29
STMICROELECTRONICS [ ST ]
