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M48T08-100MH1F View Datasheet(PDF) - STMicroelectronics

Part Name
Description
Manufacturer
M48T08-100MH1F
ST-Microelectronics
STMicroelectronics ST-Microelectronics
M48T08-100MH1F Datasheet PDF : 27 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
M48T08, M48T08Y, M48T18
OPERATION MODES
As Figure 6., page 5 shows, the static memory ar-
ray and the quartz-controlled clock oscillator of the
M48T08/18/08Y are integrated on one silicon chip.
The two circuits are interconnected at the upper
eight memory locations to provide user accessible
BYTEWIDEâ„¢ clock information in the bytes with
addresses 1FF8h-1FFFh.
The clock locations contain the year, month, date,
day, hour, minute, and second in 24 hour BCD for-
mat. Corrections for 28, 29 (leap year - valid until
2100), 30, and 31 day months are made automat-
ically. Byte 1FF8h is the clock control register. This
byte controls user access to the clock information
and also stores the clock calibration setting.
The eight clock bytes are not the actual clock
counters themselves; they are memory locations
consisting of BiPORTâ„¢ READ/WRITE memory
cells. The M48T08/18/08Y includes a clock control
circuit which updates the clock bytes with current
information once per second. The information can
be accessed by the user in the same manner as
any other location in the static memory array.
The M48T08/18/08Y also has its own Power-fail
Detect circuit. The control circuitry constantly mon-
itors the single 5V supply for an out of tolerance
condition. When VCC is out of tolerance, the circuit
write protects the SRAM, providing a high degree
of data security in the midst of unpredictable sys-
tem operation brought on by low VCC. As VCC falls
below the Battery Back-up Switchover Voltage
(VSO), the control circuitry connects the battery
which maintains data and clock operation until val-
id power returns.
Table 2. Operating Modes
Mode
VCC
E1
E2
G
Deselect
VIH
X
X
Deselect
WRITE
READ
4.75 to 5.5V
or
4.5 to 5.5V
X
VIL
X
VIL
VIH
X
VIL
VIH
VIL
READ
VIL
VIH
VIH
Deselect VSO to VPFD(min)(1)
X
X
X
Deselect
≤ VSO(1)
X
X
X
Note: X = VIH or VIL; VSO = Battery Back-up Switchover Voltage.
1. See Table 11., page 20 for details.
W
DQ0-DQ7
X
High Z
X
High Z
VIL
DIN
VIH
DOUT
VIH
High Z
X
High Z
Power
Standby
Standby
Active
Active
Active
CMOS Standby
X
High Z Battery Back-up Mode
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