M48T128 ST Microelectronics, M48T128 Datasheet - Page 2

• Manufacturer Part Number: M48T128
• Description: 3.3V-5V 1 Mbit 128Kb x8 TIMEKEEPER SRAM
• Manufacturer: ST Microelectronics

M48T128Y, M48T128V
Table 2. Absolute Maximum Ratings
Note: 1. Stresses greater than those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress
Figure 2. DIP Connections
DESCRIPTION
The M48T128Y/V TIMEKEEPER RAM is a 128Kb
x 8 non-volatile static RAM and real time clock.
The special DIP package provides a fully integrat-
ed battery back-up memory and real time clock so-
lution. The M48T128Y/V directly replaces industry
standard 128Kb x 8 SRAM.
2/14
Symbol
T
V
V
P
CAUTION: Negative undershoots below –0.3V are not allowed on any pin while in the Battery Back-up mode.
T
STG
2. Soldering temperature not to exceed 260°C for 10 seconds (total thermal budget not to exceed 150°C for longer than 30 seconds).
I
CC
O
IO
A
D
rating only and functional operation of the device at these or any other conditions above those indicated in the operational section
of this specification is not implied. Exposure to the absolute maximum rating conditions for extended periods of time may affect
reliability.
DQ0
DQ1
DQ2
V SS
A16
A14
A12
NC
A7
A6
A5
A4
A3
A2
A1
A0
Ambient Operating Temperature
Storage Temperature (V
Input or Output Voltages
Supply Voltage
Output Current
Power Dissipation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
M48T128Y
M48T128V
AI02245
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
CC
V CC
A15
NC
W
A13
A8
A9
A11
G
A10
E
DQ7
DQ6
DQ5
DQ4
DQ3
Off, Oscillator Off)
Parameter
(1)
M48T128Y
M48T128V
It also provides the non-volatility of Flash without
any requirement for special write timing or limita-
tions on the number of writes that can be per-
formed. The 32 pin 600 mil DIP Hybrid houses a
controller chip, SRAM, quartz crystal, and a long
life lithium button cell in a single package.
Figure 3 illustrates the static memory array and the
quartz controlled clock oscillator. The clock loca-
tions contain the year, month, date, day, hour,
minute, and second in 24 hour BCD format. Cor-
rections for 28, 29 (leap year), 30, and 31 day
months are made automatically. Byte 1FFF8h is
the clock control register. This byte controls user
access to the clock information and also stores the
clock calibration setting. The seven clock bytes
(1FFFFh - 1FFF8h) are not the actual clock
counters, they are memory locations consisting of
BiPORT™ read/write memory cells within the stat-
ic RAM array. The M48T128Y/V includes a clock
control circuit which updates the clock bytes with
current information once per second. The informa-
tion can be accessed by the user in the same man-
ner as any other location in the static memory
array. The M48T128Y/V also has its own Power-
Fail Detect circuit. This control circuitry constantly
monitors the supply voltage for an out of tolerance
condition. When V
write protects the TIMEKEEPER register data and
external SRAM, providing data security in the
midst of unpredictable system operation. As V
falls, the control circuitry automatically switches to
the battery, maintaining data and clock operation
until valid power is restored.
CC
–0.3 to V
is out of tolerance, the circuit
–0.3 to 7.0
–0.3 to 4.6
–40 to 70
0 to 70
Value
20
1
CC
+0.3
Unit
mA
°C
°C
W
V
V
V
CC