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AS7C4098A

2/21/06, v 1.2

Alliance Semiconductor

P. 2 of 11

Functional description

The AS7C4098A is a high-performance CMOS 4,194,304-bit Static Random Access Memory (SRAM) device organized as

262,144 words × 16 bits. It is designed for memory applications where fast data access, low power, and simple interfacing are

desired.

for high-performance applications. The chip enable input CE permits easy memory expansion with multiple-bank memory

systems.

When CE is high the device enters standby mode. The device is guaranteed not to exceed 55mW power consumption in CMOS

standby mode. A write cycle is accomplished by asserting write enable (WE) and chip enable (CE). Data on the input pins I/

O1–I/O16 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.

The device provides multiple center power and ground pins, and separate byte enable controls, allowing individual bytes to be

written and read. LB controls the lower bits, I/O1–I/O8, and UB controls the higher bits, I/O9–I/O16.

All chip inputs and outputs are TTL- and CMOS-compatible, and operation is for 5.0V (AS7C4098A) supply. The device is

available in the JEDEC standard 400-mL, 44-pin SOJ, TSOP 2 packages.

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.

Absolute maximum ratings

Parameter

Symbol

Min

Max

Unit

–0.50

+7.0

V

Voltage on any pin relative to GND

–0.50

V

Power dissipation

–1.5

W

Storage temperature (plastic)

–65

+150

°C

–55

+125

°C

DC current into outputs (low)

–±20

mA

Truth table

CE

WE

OE

LB

UB

I/O1–I/O8

I/O9–I/O16

Mode

HXXXX

High Z

High Z

L

HHXX

High Z

High Z

L

XXHH

LH

L

LH

High Z

HL

High Z

LL

LL

X

LH

High Z

HL

High Z

LL

Key: X = Don’t care, L = Low, H = High.