MM54C89 MM74C89 64-Bit TRI-STATE Random Access Read Write Memory
March 1988
MM54C89 MM74C89 64-Bit TRI-STATE
Random Access Read Write Memory
General Description
The MM54C89 MM74C89 is a 16-word by 4-bit random ac-
cess read write 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
Address inputs must be stable t
SA
pri-
or to the positive to negative transition of memory enable It
is thus not necessary to hold address information stable for
more than t
HA
after the memory is enabled (positive to neg-
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
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
Y
Y
Y
Y
Y
Y
Wide supply voltage range
3 0V to 15V
Guaranteed noise margin
1 0V
High noise immunity
0 45 V
CC
(typ )
Low power
fan out of 2
TTL compatibility
driving 74L
Low power consumption
100 nW package (typ )
Fast access time
130 ns (typ ) at V
CC
e
10V
TRI-STATE output
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
Logic and Connection Diagrams
Dual-In-Line Package
Top View
TL F 5888 鈥?2
Order Number MM54C89
or MM74C89
TL F 5888 鈥?1
TRI-STATE is a registered trademark of National Semiconductor Corporation
C
1995 National Semiconductor Corporation
TL F 5888
RRD-B30M105 Printed in U S A
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