Page 1
DATA SH EET
Product specification
File under Integrated Circuits, IC06
December 1990
INTEGRATED CIRCUITS
74HC/HCT85
4-bit magnitude comparator
For a complete data sheet, please also download:
•The IC06 74HC/HCT/HCU/HCMOS Logic Family Specifications
•The IC06 74HC/HCT/HCU/HCMOS Logic Package Information
•The IC06 74HC/HCT/HCU/HCMOS Logic Package Outlines
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December 1990 2
Philips Semiconductors Product specification
4-bit magnitude comparator 74HC/HCT85
FEATURES
• Serial or parallel expansion without extra gating
• Magnitude comparison of any binary words
• Output capability: standard
• ICC category: MSI
GENERAL DESCRIPTION
The 74HC/HCT85 are high-speed Si-gate CMOS devices
and are pin compatible with low power Schottky TTL
(LSTTL). They are specified in compliance with JEDEC
standard no. 7A.
The 74HC/HCT85 are 4-bit magnitude comparators that
can be expanded to almost any length. They perform
comparison of two 4-bit binary, BCD or other monotonic
codes and present the three possible magnitude results at
the outputs (Q
A>B
, Q
A=B
and Q
A<B
). The 4-bit inputs are
weighted (A0 to A3 and B0 to B3), where A3 and B3 are the
most significant bits.
The operation of the “85” is described in the function table,
showing all possible logic conditions. The upper part of the
table describes the normal operation under all conditions
that will occur in a single device or in a series expansion
scheme. In the upper part of the table the three outputs are
mutually exclusive. In the lower part of the table, the
outputs reflect the feed forward conditions that exist in the
parallel expansion scheme.
For proper compare operation the expander inputs (I
A>B
,
I
A=B
and I
A<B
) to the least significant position must be
connected as follows: I
A<B=IA>B
= = LOW and
I
A=B
= HIGH.
For words greater than 4-bits, units can be cascaded by
connecting outputs Q
A<B
, Q
A>Β
and Q
A=B
to the
corresponding inputs of the significant comparator.
QUICK REFERENCE DATA
GND = 0 V; T
amb
=25°C; tr=tf= 6 ns
Notes
1. C
PD
is used to determine the dynamic power dissipation (PD in µW):
PD=CPD× V
CC
2
× fi+ ∑ (CL× V
CC
2
× fo) where:
fi= input frequency in MHz
fo= output frequency in MHz
∑ (CL× V
CC
2
× fo) = sum of outputs
CL= output load capacitance in pF
VCC= supply voltage in V
2. For HC the condition is VI= GND to V
CC
For HCT the condition is VI= GND to VCC− 1.5 V
ORDERING INFORMATION
See
“74HC/HCT/HCU/HCMOS Logic Package Information”
.
SYMBOL PARAMETER CONDITIONS
TYPICAL
UNIT
HC HCT
t
PHL/ tPLH
propagation delay CL= 15 pF; VCC=5 V
A
n
, Bn to Q
A>B
, Q
A<B
20 22 ns
A
n
, Bn to Q
A=B
18 20 ns
I
A<B,
, I
A=B
, I
A>B
to Q
A<B
, Q
A>B
15 15 ns
I
A=B
to Q
A=B
11 15 ns
C
I
input capacitance 3.5 3.5 pF
C
PD
power dissipation capacitance per package notes 1 and 2 18 20 pF
Page 3
December 1990 3
Philips Semiconductors Product specification
4-bit magnitude comparator 74HC/HCT85
PIN DESCRIPTION
PIN NO. SYMBOL NAME AND FUNCTION
2I
A<B
A< B expansion input
3I
A=B
A = B expansion input
4I
A>B
A>B expansion input
5Q
A>B
A> B output
6Q
A=B
A = B output
7Q
A<B
A<B output
8 GND ground (0 V)
9, 11, 14, 1, B
0
to B
3
word B inputs
10, 12, 13, 15 A
0
to A
3
word A inputs
16 V
CC
positive supply voltage
Fig.1 Pin configuration. Fig.2 Logic symbol. Fig.3 IEC logic symbol.
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December 1990 4
Philips Semiconductors Product specification
4-bit magnitude comparator 74HC/HCT85
APPLICATIONS
• Process controllers
• Servo-motor control
FUNCTION TABLE
Notes
1. H = HIGH voltage level
L = LOW voltage level
X = don’t care
COMPARING INPUTS CASCADING INPUTS OUTPUTS
A
3
, B
3
A2, B
2
A1, B
1
A0, B
0
I
A>B
I
A<B
I
A=B
Q
A>B
Q
A<B
Q
A=B
A3>B
3
A3<B
3
A3=B
3
A3=B
3
X
X
A2>B
2
A2<B
2
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
H
L
H
L
L
H
L
H
L
L
L
L
A
3=B3
A3=B
3
A3=B
3
A3=B
3
A2=B
2
A2=B
2
A2=B
2
A2=B
2
A1>B
1
A1<B
1
A1=B
1
A1=B
1
X
X
A0>B
0
A0<B
0
X
X
X
X
X
X
X
X
X
X
X
X
H
L
H
L
L
H
L
H
L
L
L
L
A
3=B3
A3=B
3
A3=B
3
A2=B
2
A2=B
2
A2=B
2
A1=B
1
A1=B
1
A1=B
1
A0=B
0
A0=B
0
A0=B
0
H
L
L
L
H
L
L
L
H
H
L
L
L
H
L
L
L
H
A
3=B3
A3=B
3
A3=B
3
A2=B
2
A2=B
2
A2=B
2
A1=B
1
A1=B
1
A1=B
1
A0=B
0
A0=B
0
A0=B
0
X
H
L
X
H
L
H
L
L
L
L
H
L
L
H
H
L
L
Fig.4 Functional diagram.
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December 1990 5
Philips Semiconductors Product specification
4-bit magnitude comparator 74HC/HCT85
Fig.5 Logic diagram.
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December 1990 6
Philips Semiconductors Product specification
4-bit magnitude comparator 74HC/HCT85
DC CHARACTERISTICS FOR 74HC
For the DC characteristics see
“74HC/HCT/HCU/HCMOS Logic Family Specifications”
.
Output capability: standard
ICC category: MSI
AC CHARACTERISTICS FOR 74HC
GND = 0 V; t
r=tf
= 6 ns; CL= 50 pF
SYMBOL PARAMETER
T
amb
(°C) TEST CONDITIONS
74HC
UNIT
V
CC
(V)
WAVEFORMS+25 −40 to +85 −40 to +125
min. typ. max. min. max. min. max.
t
PHL
/ t
PLH
propagation delay
An, Bn to Q
A>B
or Q
A<B
63
23
18
195
39
33
245
49
42
295
59
50
ns 2.0
4.5
6.0
Fig.6
t
PHL
/ t
PLH
propagation delay
An, Bn to Q
A=B
58
21
17
175
35
30
220
44
37
265
53
45
ns 2.0
4.5
6.0
Fig.6
t
PHL
/ t
PLH
propagation delay
I
A<B
, I
A=B
, I
A>B
to
Q
A<B
, Q
A>B
50
18
14
140
28
24
175
35
30
210
42
36
ns 2.0
4.5
6.0
Fig.6
t
PHL
/ t
PLH
propagation delay
I
A=B
to Q
A=B
39
14
11
120
24
20
150
30
26
180
36
31
ns 2.0
4.5
6.0
Fig.6
t
THL
/ t
TLH
output transition time 19
7
6
75
15
13
95
19
16
110
22
19
ns 2.0
4.5
6.0
Fig.6
Page 7
December 1990 7
Philips Semiconductors Product specification
4-bit magnitude comparator 74HC/HCT85
DC CHARACTERISTICS FOR 74HCT
For the DC characteristics see
“74HC/HCT/HCU/HCMOS Logic Family Specifications”
.
Output capability: standard
ICC category: MSI
Note to HCT types
The value of additional quiescent supply current (∆I
CC
) for a unit load of 1 is given in the family specifications.
To determine ∆ICC per input, multiply this value by the unit load coefficient shown in the table below.
AC CHARACTERISTICS FOR 74HCT
GND = 0 V; tr=tf= 6 ns; CL= 50 pF
INPUT UNIT LOAD COEFFICIENT
I
A<B
I
A>B
I
A=B
An, B
n
1.00
1.00
1.50
1.50
SYMBOL PARAMETER
T
amb
(°C) TEST CONDITIONS
74HCT
UNIT
V
CC
(V)
WAVEFORMS+25 −40 to +85 −40 to +125
min. typ. max. min. max. min. max.
t
PHL
/ t
PLH
propagation delay
An, Bn to Q
A>B
or Q
A<B
26 44 55 66 ns 4.5 Fig.6
t
PHL
/ t
PLH
propagation delay
An, Bn to Q
A=B
24 40 50 60 ns 4.5 Fig.6
t
PHL
/ t
PLH
propagation delay
I
A<B
, I
A=B
, I
A>B
to
Q
A<B
, Q
A>B
18 31 39 47 ns 4.5 Fig.6
t
PHL
/ t
PLH
propagation delay
I
A=B
to Q
A=B
18 31 39 47 ns 4.5 Fig.6
t
THL
/ t
TLH
output transition time 7 15 19 22 ns 4.5 Fig.6
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December 1990 8
Philips Semiconductors Product specification
4-bit magnitude comparator 74HC/HCT85
AC WAVEFORMS
APPLICATION INFORMATION
Fig.6 Waveforms showing the word A inputs (An), word B inputs (Bn) and expansion inputs (In) to the outputs
(Qn) propagation delays and the output transition times.
(1) HC : VM= 50%; VI= GND to VCC.
HCT: V
M
= 1.3 V; VI= GND to 3 V.
Fig.7 Series cascading; comparing 12-bit words.
Page 9
December 1990 9
Philips Semiconductors Product specification
4-bit magnitude comparator 74HC/HCT85
PACKAGE OUTLINES
See
“74HC/HCT/HCU/HCMOS Logic Package Outlines”
.
Fig.8 Parallel cascading; comparing 12-bit words.
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