®
AS7C1025
AS7C31025
3/23/01; v.1.0 Alliance Semiconductor P. 2 of 9
Functional description
The AS7C1025 and AS7C31025 are high-performance CMOS 1,048,576-bit Static Random Access Memory (SRAM) devices
organized as 131,072 words × 8 bits. They are designed for memory applications where fast data access, low power, and
simple interfacing are desired.
Equal address access and cycle times (tAA, tRC, tWC) of 12/15/20 ns with output enable access times (tOE) of 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 devices enter standby mode. The standard AS7C1025 is guaranteed not to exceed 27.5 mW power
consumption in standby mode, and typically requires only 5 mW. Both devices also offer 2.0V data retention.
A write cycle is accomplished by asserting write enable (
WE
) and chip enable (
CE
). Data on the input pins I/O0-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 chips
drive 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 5V supply (AS7C1025) or 3.3V supply
(AS7C31025). The AS7C1025 and AS7C31025 are 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 functional
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 Device Symbol Min Max Unit
Vo ltag e o n V CC relative to GND AS7C1025 Vt1 –0.50 +7.0 V
AS7C31025 Vt1 –0.50 +5.0 V
Voltage on any pin relative to GND Vt2 –0.50 VCC + 0.5 V
Power dissipation PD–1.0W
Storage temperature (plastic) Tstg –65 +150 oC
Ambient temperature with VCC applied Tbias –55 +125 oC
DC current into outputs (low) IOUT –20mA
CE WE OE
Data Mode
H X X High Z Standby (ISB, ISB1)
L H H High Z Output disable (ICC)
LHL D
OUT Read (ICC)
LLX D
IN Write (ICC)