Fairchild Semiconductor MM74C89N Datasheet

October 1987
Revised January 1999

MM74C89
64-Bit 3-STATE Random Access Read/Write Memory

MM74C89 64-Bit 3-STATE Random Access Read/Write Memory

General Description

The MM74C89 is a 16- word by 4-bit random access read/
write memory. Inputs to the memory consist of four address
lines, four data input lines, a write
ory enable line. The four binary address inputs are
decoded internally to select each of the 16 possible word
locations. An interna l address r egister la tches the a ddress
information on the positive to negative transition of the
memory enable inpu t. The four 3-STATE data output lines
working in conjunct ion with the memor y enable input pro­vide for easy memory expansion.

Address Operation: Address inputs must be stable t
prior to the positive to negative transition of memory

enable. It is thus not necessary to hold address information
stable for more than t

tive to negative transition of memory
Write Operation: Informa tion present at the data inp uts is

written into the memory at the selected address by bringing

enable and memory enable LOW.

write

after the memory is enabled (posi-

HA

enable line and a mem-

enable).

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 desired addre ss and br i n ging mem ory
LOW and write enable HIGH.

When the device is writing or disa bled the ou tput assu mes
a 3-STATE (Hi-z) condition.

Features

■ Wide supply voltage range: 3.0V to 15V

■ Guaranteed noise margin: 1.0V

SA

■ High noise immunity: 0.45 V

■ Low power TTL compatibility:

fan out of 2 driving 74L

■ Low power consumption: 100 nW/package (typ.)

■ Fast access time: 130 ns (typ.) at V

■ 3-STATE output

Note: The timing is dif fere nt t han the DM7489 in that a positive to negative
transition of the memory

enable must occur for the memory to be selected.

CC

(typ.)

CC

= 10V

Ordering Code:

Order Number Package Number Package Description

MM74C89N N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide

Connection Diagram

Pin Assignments for DIP

Truth T able

ME WE Operation Condition of Outputs

LLWrite 3-STATE
L H Read Complement of Selected Word
H L Inhibit, Storage 3-STATE
H H Inhibit, Storage 3-STATE

enable

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Logic Diagram

MM74C89

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