M48T08 ST Microelectronics, M48T08 Datasheet - Page 7

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

Table 10. Write Mode AC Characteristics (T
DESCRIPTION (cont’d)
day, hour, minute, and second in 24 hour BCD
format. Corrections for 28, 29 (leap year), 30, and
31 day months are made automatically.
1FF8h is the clock control register. This byte con-
trols user access to the clock information and also
stores the clock calibration setting.
The clock locations contain the year, month, date,
Symbol
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
E1LE1H
E2HE2L
t
t
t
E1HAX
DVE1H
E1HDX
t
AVE2H
E2LAX
DVE2L
E2LDX
AVE1H
WHQX
AVE1L
WLWH
WHAX
DVWH
WHDX
WLQZ
AVWH
AVE2L
AVWL
AVAV
Write Cycle Time
Address Valid to Write Enable Low
Address Valid to Chip Enable 1 Low
Address Valid to Chip Enable 2 High
Write Enable Pulse Width
Chip Enable 1 Low to Chip Enable 1 High
Chip Enable 2 High to Chip Enable 2 Low
Write Enable High to Address Transition
Chip Enable 1 High to Address Transition
Chip Enable 2 Low to Address Transition
Input Valid to Write Enable High
Input Valid to Chip Enable 1 High
Input Valid to Chip Enable 2 Low
Write Enable High to Input Transition
Chip Enable 1 High to Input Transition
Chip Enable 2 Low to Input Transition
Write Enable Low to Output Hi-Z
Address Valid to Write Enable High
Address Valid to Chip Enable 1 High
Address Valid to Chip Enable 2 Low
Write Enable High to Output Transition
Parameter
Byte
A
= 0 to 70 C; V
The eight clock bytes are not the actual clock
counters themselves; they are memory locations
consisting of BiPORT
The M48T08/18 includes a clock control circuit
which updates the clock bytes with current informa-
tion once per second. The information can be
accessed by the user in the same manner as any
other location in the static memory array.
Min
100
80
80
80
10
10
10
50
50
50
80
80
80
10
0
5
0
0
5
5
CC
-100
= 4.75V to 5.5V or 4.5V to 5.5V)
M48T08 / M48T18
Max
50
Min
150
100
130
130
130
130
130
read/write memory cells.
10
10
70
70
10
70
10
0
0
0
5
5
5
-150
M48T08, M48T18
Max
70
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
7/19