AS7C31025B
3/24/04, v. 1.3 Alliance Semiconductor P. 2 of 9
®
Functional description
The AS7C31025B is a high-performance CMOS 1,048,576-bit Static Random Access Memory (SRAM) device organized as 131,072 x 8
bits. It is designed for memory applications where fast data access, low power, and simple interfacing are desired.
Equal address access and cycle times (t
AA
, t
RC
, t
WC
) of 10/12/15/20 ns with output enable access times (t
OE
) of 5, 6, 7, 8 ns are ideal for
high-performance applications. The chip enable input CE permits easy memory and expansion with multiple-bank memory systems.
When
CE
is high the device enters standby mode. A write cycle is accomplished by asserting write enable (
WE
) and chip enable (
CE
). Data
on the input pins I/O0 through I/O7 is written on the rising edge of
WE
(write cycle 1) or
CE
(write cycle 2). To avoid bus contention,
external devices should drive I/O pins only after outputs have been disabled with output enable (
OE
) or write enable (
WE
).
A read cycle is accomplished by asserting output enable (
OE
) and chip enable (
CE
), with write enable (
WE
) high. The chip drives I/O pins
with the data word referenced by the input address. When either chip enable or output enable is inactive or write enable is active, output
drivers stay in high-impedance mode.
All chip inputs and outputs are TTL-compatible, and operation is from a single 3.3 V supply. The AS7C31025B is packaged in common
industry standard packages.
Absolute maximum ratings
NOTE: Stresses greater than those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and func-
tional operation of the device at these or any other conditions outside those indicated in the operational sections of this specification is not implied. Exposure
to absolute maximum rating conditions for extended periods may affect reliability.
Truth table
Key: X = don’t care, L = low, H = high.
Parameter Symbol Min Max Unit
Voltage on V
CC
relative to GND V
t1
–0.50 +5.0 V
Voltage on any pin relative to GND V
t2
–0.50 V
CC
+ 0.5 V
Power dissipation P
D
–1.0W
Storage temperature (plastic) T
stg
–65 +150
o
C
Ambient temperature with V
CC
applied T
bias
–55 +125
o
C
DC current into outputs (low) I
OUT
–20mA
CE WE OE
Data Mode
H X X High Z Standby (I
SB
, I
SB1
)
L H H High Z Output disable (I
CC
)
LHL D
OUT
Read (I
CC
)
LLX D
IN
Write (I
CC
)
