SN54LS85 Datasheet, PDF (1/4 Pages) Motorola, Inc – 4-BIT MAGNITUDE COMPARATOR

4-BIT MAGNITUDE
COMPARATOR
The SN54/ 74LS85 is a 4-Bit Magnitude Camparator which compares two
4-bit words (A, B), each word having four Parallel Inputs (A0 – A3, B0 – B3); A3,
B3 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” (OA _{> B),} “A less than B” (OA _{< B),} “A equal to B”
(OA _{= B).} Three Expander Inputs, IA _{> B,} IA _{< B,} IA _{= B,} allow cascading without
external gates. For proper compare operation, the Expander Inputs to the
least significant position must be connected as follows: IA _{< B=} IA _{> B} = L, IA _{= B}
= H. For serial (ripple) expansion, the OA _{> B,} OA _{< B} and OA _{= B} Outputs are
connected respectively to the IA _{> B,} IA _{< B,} and IA _{= 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
SN54 / 74LS85 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
• OA _{> B,} OA _{< B,} and OA _{= B} Outputs Available
CONNECTION DIAGRAM DIP (TOP VIEW)
VCC A3 B2 A2 A1 B1 A0 B0
16 15 14 13 12 11 10 9
1 2 3 4 56 78
B3 IA<B IA=B IA>B OA>B OA=B ^OA<B GND
NOTE:
The Flatpak version has the
same pinouts (Connection
Diagram) as the Dual In-Line
Package.
PIN NAMES
LOADING (Note a)
HIGH
LOW
A0 – A3, B0 – B3
IA _{= B}
IA _{< B,} IA _{> B}
OA _{> B}
OA _{< B}
OA _{= B}
Parallel Inputs
A = B Expander Inputs
A < B, A > B, Expander Inputs
A Greater Than B Output (Note b)
B Greater Than A Output (Note b)
A Equal to B Output (Note b)
1.5 U.L.
1.5 U.L.
0.5 U.L.
10 U.L.
10 U.L.
10 U.L.
0.75 U.L.
0.75 U.L.
0.25 U.L.
5 (2.5) U.L.
5 (2.5) U.L.
5 (2.5) U.L.
NOTES:
a) 1 TTL Unit Load (U.L.) = 40 µA HIGH/1.6 mA LOW.
b) The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial (74)
Temperature Ranges.
SN54/74LS85
4-BIT MAGNITUDE
COMPARATOR
LOW POWER SCHOTTKY
16
1
J SUFFIX
CERAMIC
CASE 620-09
16
1
N SUFFIX
PLASTIC
CASE 648-08
16
1
D SUFFIX
SOIC
CASE 751B-03
ORDERING INFORMATION
SN54LSXXJ
SN74LSXXN
SN74LSXXD
Ceramic
Plastic
SOIC
LOGIC SYMBOL
10 12 13 15 9 11 14 1
A0 A1 A2 A3 B0 B1 B2 B3
4 IA>B
OA>B 5
2 IA<B
OA<B 7
3 IA=B
OA=B ₆
VCC = PIN 16
GND = PIN 8
FAST AND LS TTL DATA
5-84