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ALLIANCE SEMICONDUCTOR

10/6/00

AS6VA25616

Functional description

The AS6VA25616 is a low-power 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 slow data access, low power, and simple interfacing are desired.

permit easy memory expansion with multiple-bank memory systems.

When CS is high, or UB and LB are high, the device enters standby mode: the AS6VA25616 is guaranteed not to exceed 66

µW power

A write cycle is accomplished by asserting write enable (WE) and chip select (CS) low, and UB and/or LB low. Data on the input pins

I/O1–O16 is written on the rising edge of WE (write cycle 1) or CS (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), chip select (CS), UB and LB low, with write enable (WE) high. The chip

drives I/O pins with the data word referenced by the input address. When either chip select or output enable is inactive, or write enable is

active, or (UB) and (LB), output drivers stay in high-impedance mode.

These devices provide 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 CMOS-compatible, and operation is from a single 2.7V to 3.3V supply. Device is available in the JEDEC

standard 400-mm, TSOP II, and 48-ball FBGA 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

–0.5

V

Voltage on any I/O pin relative to GND

–0.5

V

Power dissipation

–1.0

W

Storage temperature (plastic)

–65

+150

–55

+125

DC output current (low)

–20

mA

CS

WE

OE

LB

UB

Supply

Current

I/O1–I/O8

I/O9–I/O16

Mode

HX

XX

X

High Z

High Z

LX

X

H

H

LH

H

X

X

High Z

High Z

LH

L

LH

High Z

H

L

High Z

LL

LL

X

LH

High Z

H

L

High Z

LL