M48Z128Y 查看數據表（PDF） - STMicroelectronics
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M48Z128Y Datasheet PDF : 17 Pages
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Figure 3. Block Diagram
M48Z128, M48Z128Y
VCC
POWER
131,072 x 8
VOLTAGE SENSE
E
AND
SRAM ARRAY
SWITCHING
E
CIRCUITRY
INTERNAL
BATTERY
VSS
A0-A16
DQ0-DQ7
W
G
AI01196
The unique design allows the SNAPHAT battery
package to be mounted on top of the SOIC pack-
age after the completion of the surface mount pro-
cess. Insertion of the SNAPHAT housing after
reflow prevents potential battery damage due to
the high temperatures required for device surface-
mounting. The SNAPHAT housing is keyed to pre-
vent reverse insertion.
The SNAPHAT battery package is shipped sepa-
rately in plastic anti-static tubes or in Tape & Reel
form. The part number is ”M4Z28-BRxxSH1”.
The M48Z128/128Y 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 approximately 3V, the control circuitry con-
nects the battery which maintains data until valid
power returns.
READ MODE
The M48Z128/128Y is in the Read Mode whenev-
er W (Write Enable) is high and E (Chip Enable) is
low. The device architecture allows ripple-through
access of data from eight of 1,048,576 locations in
the static storage array. Thus, the unique address
specified by the 17 Address Inputs defines which
one of the 131,072 bytes of data is to be accessed.
Valid data will be available at the Data I/O pins
within Address Access time (tAVQV) after the last
address input signal is stable, providing that the E
and G (Output Enable) access times are also sat-
isfied. If the E and G access times are not met, val-
id data will be available after the later of Chip
Enable Access time (tELQV) or Output Enable Ac-
cess Time (tGLQV). The state of the eight three-
state Data I/O signals is controlled by E and G. If
the outputs are activated before tAVQV, the data
lines will be driven to an indeterminate state until
tAVQV. If the Address Inputs are changed while E
and G remain low, output data will remain valid for
Output Data Hold time (tAXQX) but will go indeter-
minate until the next Address Access.
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