AS7C256

AS7C256L

2

The AS7C256 is a high performance CMOS 262,144-bit

Static Random Access Memory (SRAM) organized as

32,768 words

× 8 bits. It is designed for memory applica-

tions where fast data access, low power, and simple interfac-

ing are desired.

of 3/3/4/5/6/8 ns are ideal for high performance applica-

tions. A chip enable (CE) input permits easy memory

expansion with multiple-bank memory organizations.

When CE is HIGH the device enters standby mode. The

standard AS7C256 is guaranteed not to exceed 11 mW

power consumption in standby mode; the L version is guar-

anteed not to exceed 2.75 mW, and typically requires only

500

µW. The L version also offers 2.0V data retention, with

maximum power consumption in this mode of 300

µW.

A write cycle is accomplished by asserting chip enable (CE)

and write enable (WE) LOW. 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 chip enable (CE)

and output enable (OE) LOW, with write enable (WE)

HIGH. The chip drives I/O pins with the data word refer-

enced by the input address. When chip enable or output

enable is HIGH, or write enable is LOW, output drivers stay

in high-impedance mode.

All chip inputs and outputs are TTL-compatible, and opera-

tion is from a single 5V supply. The AS7C256 is packaged

in all high volume industry standard packages.

FUNCTIONAL DESCRIPTION

.

Parameter

Symbol

Min

Max

Unit

Voltage on Any Pin Relative to GND

–0.5

+7.0

V

Power Dissipation

–

1.0

W

Storage Temperature (Plastic)

–55

+150

Temperature Under Bias

–10

+85

DC Output Current

–20

mA

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.

CE

WE

OE

Data

Mode

HXXHigh Z

L

H

H

High Z

Output Disable

LH

Read

LLX

Write

Key: X = Don’t Care, L = LOW, H = HIGH

ABSOLUTE MAXIMUM RATINGS

TRUTH TABLE