TLF5888

March 1988

MM54C89MM74C89 64-Bit TRI-STATE

Random Access ReadWrite Memory

General Description

The MM54C89MM74C89 is a 16-word by 4-bit random ac-

cess readwrite memory Inputs to the memory consist of

four address lines four data input lines a write enable line

and a memory enable line The four binary address inputs

are decoded internally to select each of the 16 possible

word locations An internal address register latches the ad-

dress information on the positive to negative transition of

the memory enable input The four TRI-STATE data output

lines working in conjunction with the memory enable input

provide for easy memory expansion

Address Operation

or to the positive to negative transition of memory enable It

is thus not necessary to hold address information stable for

ative transition of memory enable)

Note

The timing is different than the DM7489 in that a positive to negative

transition of the memory enable must occur for the memory to be

selected

Write Operation

Information present at the data inputs is

written into the memory at the selected address by bringing

write enable and memory enable low

Read Operation

The complement of the information which

was written into the memory is non-destructively read out at

the four outputs This is accomplished by selecting the de-

sired address and bringing memory enable low and write

enable high

When the device is writing or disabled the output assumes a

TRI-STATE (Hi-z) condition

Features

Y

Wide supply voltage range

30V to 15V

Y

Guaranteed noise margin

10V

Y

High noise immunity

Y

Low power

fan out of 2

TTL compatibility

driving 74L

Y

Low power consumption

100 nWpackage (typ)

Y

Fast access time

Y

TRI-STATE output

Logic and Connection Diagrams

TLF5888 – 1

Dual-In-Line Package

TLF5888 – 2

Top View

Order Number MM54C89

or MM74C89

TRI-STATE

is a registered trademark of National Semiconductor Corporation

C1995 National Semiconductor Corporation

RRD-B30M105Printed in U S A