FAIRCHILD MM74C85

Revised May 2002
MM74C85
4-Bit Magnitude Comparator
General Description
Features
The MM74C85 is a four-bit magnitude comparator which
will perform comparison of straight binary or BCD codes.
The circuit consists of eight comparing inputs (A0, A1, A2,
A3, B0, B1, B2, B3), three cascading inputs (A > B, A < B
and A = B), and three outputs (A > B, A < B and A = B).
This device compares two four-bit words (A and B) and
determines whether they are “greater than,” “less than,” or
“equal to” each other by a high level on the appropriate output. For words greater than four-bits, units can be cascaded by connecting the outputs (A > B, A < B, and A = B)
of the least significant stage to the cascade inputs (A > B, A
< B and A = B) of the next-significant stage. In addition the
least significant stage must have a high level voltage
(VIN(1)) applied to the A = B input and low level voltage
(VIN(0)) applied to A > B and A < B inputs.
■ Wide supply voltage range:
3.0V to 15V
■ Guaranteed noise margin: 1.0V
■ High noise immunity: 0.4 VCC (typ.)
■ Low power:
TTL compatibility:
fan out of 2 driving 74L
■ Expandable to 'N' stages
■ Applicable to binary or BCD
■ Low power pinout: 74L85
Ordering Code:
Order Number
MM74C85N
Package Number
N16E
Package Description
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Connection Diagram
Top View
© 2002 Fairchild Semiconductor Corporation
DS005886
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MM74C85 4-Bit Magnitude Comparator
October 1987
MM74C85
Truth Table
Comparing Inputs
Cascading Inputs
Outputs
A2, B2
A1, B1
A0, B0
A>B
A<B
A=B
A>B
A<B
A3 > B3
X
X
X
X
X
X
H
L
L
A3 < B3
X
X
X
X
X
X
L
H
L
A3 = B3
A2 > B2
X
X
X
X
X
H
L
L
A3 = B3
A2 < B2
X
X
X
X
X
L
H
L
A3, B3
A=B
A3 = B3
A2 = B2
A1 > B1
X
X
X
X
H
L
L
A3 = B3
A2 = B2
A1 < B1
X
X
X
X
L
H
L
A3 = B3
A2 = B2
A1 = B1
A0 > B0
X
X
X
H
L
L
A3 = B3
A2 = B2
A1 = B1
A0 < B0
X
X
X
L
H
L
A3 = B3
A2 = B2
A1 = B1
A0 = B0
H
L
L
H
L
L
A3 = B3
A2 = B2
A1 = B1
A0 = B0
L
H
L
L
H
L
A3 = B3
A2 = B2
A1 = B1
A0 = B0
L
L
H
L
L
H
A3 = B3
A2 = B2
A1 = B1
A0 = B0
L
H
H
L
H
H
A3 = B3
A2 = B2
A1 = B1
A0 = B0
H
L
H
H
L
H
A3 = B3
A2 = B2
A1 = B1
A0 = B0
H
H
H
H
H
H
A3 = B3
A2 = B2
A1 = B1
A0 = B0
H
H
L
H
H
L
A3 = B3
A2 = B2
A1 = B1
A0 = B0
L
L
L
L
L
L
H = HIGH Level, L = LOW Level, X = Irrelevant
Logic Diagram
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Voltage at Any Pin
Lead Temperature
−0.3V to VCC + 0.3V
Operating Temperature Range
−55°C to +125°C
Storage Temperature Range
−65°C to +150°C
Dual-In-Line
700 mW
Small Outline
500 mW
260°C
(Soldering, 10 seconds)
Note 1: “Absolute Maximum Ratings” are those values beyond which the
safety of the device cannot be guaranteed. Except for “Operating Temperature Range” they are not meant to imply that the devices should be operated at these limits. The table of “Electrical Characteristics” provides
conditions for actual device operation.
Power Dissipation (PD)
Operating VCC Range
18V
VCC
3.0V to 15V
DC Electrical Characteristics
Min/Max limits apply across temperature range unless otherwise noted
Symbol
Parameter
Conditions
Min
Typ
Max
Units
CMOS TO CMOS
VIN(1)
VIN(0)
VOUT(1)
VOUT(0)
Logical “1” Input Voltage
Logical “0” Input Voltage
Logical “1” Output Voltage
Logical “0” Output Voltage
VCC = 5.0V
3.5
VCC = 10V
8.0
V
VCC = 5.0V
1.5
VCC = 10V
2.0
VCC = 5.0V, IO = −10 µA
4.5
VCC = 10V, IO = −10 µA
9.0
V
VCC = 5.0V, IO = +10 µA
0.5
VCC = 10V, IO = +10 µA
1.0
IIN(1)
Logical “1” Input Current
VCC = 15V, VIN = 15V
IIN(0)
Logical “0” Input Current
VCC = 15V, VIN = 0V
ICC
Supply Current
VCC = 15V
0.005
−1.0
V
1.0
−0.005
0.05
V
µA
µA
300
µA
0.8
V
CMOS/LPTTL INTERFACE
VIN(1)
Logical “1” Input Voltage
VCC = 4.75V
VIN(0)
Logical “0” Input Voltage
VCC = 4.75V
VCC − 1.5
VOUT(1)
Logical “1” Output Voltage
VCC = 4.75V, IO = −360 µA
VOUT(0)
Logical “0” Output Voltage
VCC = 4.75V, IO = 360 µA
V
2.4
V
0.4
V
OUTPUT DRIVE (See Family Characteristics Data Sheet) (Short Circuit Current)
ISOURCE
ISOURCE
ISINK
ISINK
Output Source Current
VCC = 5.0V, VOUT = 0V
(P-Channel)
TA = 25°C
Output Source Current
VCC = 10V, VOUT = 0V
(P-Channel)
TA = 25°C
Output Sink Current
VCC = 5.0V, VOUT = VCC
(N-Channel)
TA = 25°C
Output Sink Current
VCC = 10V, VOUT = VCC
(N-Channel)
TA = 25°C
AC Electrical Characteristics
−3.3
mA
−8.0
−15
mA
1.75
3.6
mA
8.0
16
mA
Min
(Note 2)
TA = 25°C, CL = 50 pF, unless otherwise specified
Symbol
Parameter
tpd
−1.75
Typ
Max
Propagation Delay from any A
VCC = 50V
Conditions
250
600
or B Data Input to any Data Output
VCC = 10V
100
300
Units
ns
Propagation Delay Time from
VCC = 50V
200
500
any Cascade Input to any Output
VCC = 10V
100
250
CIN
Input Capacitance
Any Input
5.0
pF
CPD
Power Dissipation Capacitance
Per Package (Note 4)
45
pF
tpd
ns
Note 2: AC Parameters are guaranteed by DC correlated testing.
Note 3: Capacitance is guaranteed by periodic testing.
Note 4: CPD determines the no load AC power consumption of any CMOS device. For complete explanation see Family Characteristics application note,
AN-90.
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MM74C85
Absolute Maximum Ratings(Note 1)
MM74C85
Typical Applications
Four Digit Comparator
Switching Time Waveforms
Unused inputs must be tied to an appropriate logic level.
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MM74C85 4-Bit Magnitude Comparator
Physical Dimensions inches (millimeters) unless otherwise noted
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Package Number N16E
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and
Fairchild reserves the right at any time without notice to change said circuitry and specifications.
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FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD
SEMICONDUCTOR CORPORATION. As used herein:
2. A critical component in any component of a life support
device or system whose failure to perform can be reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the
body, or (b) support or sustain life, and (c) whose failure
to perform when properly used in accordance with
instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the
user.
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