AS7C31024B
3/24/04, v.1.2 Alliance Semiconductor P. 2 of 9
®
Functional description
The AS7C31024B is a high performance CMOS 1,048,576-bit Static Random Access Memory (SRAM) device organized as 131,072 words
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. Active high and low chip enables (CE1, CE2) permit easy memory expansion with multiple-bank systems.
When CE1 is high or CE2 is low, the device enters standby mode. If inputs are still toggling, the device will consume I
SB
power. If the bus is
static, then full standby power is reached (I
SB1
). For example, the AS7C31024B is guaranteed not to exceed 18 mW under nominal full
standby conditions.
A write cycle is accomplished by asserting write enable (WE) and both chip enables (CE1, CE2). Data on the input pins I/O0 through I/O7 is
written on the rising edge of WE
(write cycle 1) or the active-to-inactive edge of CE1 or CE2 (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 both chip enables (CE1, CE2), 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.
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.
Key: X = don’t care, L = low, H = high
Absolute maximum ratings
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
+0.50 V
Power dissipation P
D
–1.0W
Storage temperature (plastic) T
stg
–65 +150 °C
Ambient temperature with V
CC
applied T
bias
–55 +125 °C
DC current into outputs (low) I
OUT
–20mA
Truth table
CE1
CE2
WE OE
Data Mode
HXXX High Z Standby (I
SB
, I
SB1
)
X L X X High Z Standby (I
SB
, I
SB1
)
L H H H High Z Output disable (I
CC
)
LHHL D
OUT
Read (I
CC
)
LHLX D
IN
Write (
ICC
)
