M48T08 ST Microelectronics, M48T08 Datasheet - Page 3

• Manufacturer Part Number: M48T08
• Description: 64 Kbit 8Kb x 8 TIMEKEEPER SRAM
• Manufacturer: ST Microelectronics

Figure 3. Block Diagram
DESCRIPTION
The M48T08/18 TIMEKEEPER
non-volatile static RAM and real time clock which
is pin and functional compatible with the DS1643.
The monolithic chip is available in two special
packages to provide a highly integrated battery
backed-up memory and real time clock solution.
The M48T08/18 is a non-volatile pin and function
equivalent to any JEDEC standard 8K 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
M48T08/18 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 re-
quired for device surface-mounting. The SNAPHAT
housing is keyed to prevent reverse insertion.
32,768 Hz
CRYSTAL
LITHIUM
CELL
OSCILLATOR AND
VOLTAGE SENSE
V CC
CLOCK CHAIN
SWITCHING
®
CIRCUITRY
RAM is an 8K x 8
AND
houses the
INT
POWER
V PFD
Table 4. AC Measurement Conditions
Note that Output Hi-Z is defined as the point where data is no
longer driven.
Figure 4. AC Testing Load Circuit
Input Rise and Fall Times
Input Pulse Voltages
Input and Output Timing Ref. Voltages
C L includes JIG capacitance
DEVICE
UNDER
TEST
SRAM ARRAY
SRAM ARRAY
8 x 8 BiPORT
8184 x 8
V SS
1k
M48T08, M48T18
5V
A0-A12
DQ0-DQ7
E1
E2
W
G
1.8k
AI01333
C L = 100pF
0 to 3V
1.5V
5ns
AI01019
OUT
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