SN74LS85
4-Bit Magnitude
Comparator
The SN74LS85 is a 4-Bit Magnitude Camparator which compares
two 4-bit words (A, B), each word having four Parallel Inputs
(A
0
– A
3
, B
0
– B
3
); A
3
, B
3
being the most significant inputs. Operation
is not restricted to binary codes, the device will work with any
monotonic code. Three Outputs are provided: “A greater than B”
(O
A > B
), “A less than B” (O
A < B
), “A equal to B” (O
A = B
). Three
Expander Inputs, I
A > B
, I
A < B
, I
A = B
, allow cascading without external
gates. For proper compare operation, the Expander Inputs to the least
significant position must be connected as follows: I
A < B
= I
A > B
= L,
I
A = B
= H. For serial (ripple) expansion, the O
A > B
, O
A < B
and O
A = B
Outputs are connected respectively to the I
A > B
, I
A < B
, and I
A = B
Inputs of the next most significant comparator, as shown in Figure 1.
Refer to Applications section of data sheet for high speed method of
comparing large words.
The Truth Table on the following page describes the operation of the
SN74LS85 under all possible logic conditions. The upper 11 lines
describe the normal operation under all conditions that will occur in a
single device or in a series expansion scheme. The lower five lines
describe the operation under abnormal conditions on the cascading
inputs. These conditions occur when the parallel expansion technique
is used.
•
Easily Expandable
•
Binary or BCD Comparison
•
O
A > B
, O
A < B
, and O
A = B
Outputs Available
GUARANTEED OPERATING RANGES
Symbol
V
CC
T
A
I
OH
I
OL
Parameter
Supply Voltage
Operating Ambient
Temperature Range
Output Current – High
Output Current – Low
Min
4.75
0
Typ
5.0
25
Max
5.25
70
– 0.4
8.0
Unit
V
°C
mA
mA
http://onsemi.com
LOW
POWER
SCHOTTKY
16
1
PLASTIC
N SUFFIX
CASE 648
16
1
SOIC
D SUFFIX
CASE 751B
ORDERING INFORMATION
Device
SN74LS85N
SN74LS85D
Package
16 Pin DIP
16 Pin
Shipping
2000 Units/Box
2500/Tape & Reel
©
Semiconductor Components Industries, LLC, 1999
1
December, 1999 – Rev. 6
Publication Order Number:
SN74LS85/D
ONSEMI [ ON SEMICONDUCTOR ]
