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MM54HCT688/MM74HCT688 8-Bit Magnitude Comparator (Equality Detector)
February 1988
MM54HCT688/MM74HCT688
8-Bit Magnitude Comparator (Equality Detector)
General Description
This equality detector utilizes advanced silicon-gate CMOS
technology to compare bit for bit two 8-b
it wor
ds and indi-
cate whether or not they are equal. The P
e
Q output indi-
cates equality when it is low. A single active low enable is
provided to facilitate cascading of several packages and en-
able comparison of words greater than 8 bits.
This device is useful in memory block decoding applica-
tions, where memory block enable signals must be generat-
ed from computer address information.
The comparator combines the low power consumption of
CMOS, but inputs are compatible with TTL logic levels, and
the output can drive 10 low power Schottky equivalent
loads.
MM54HCT/MM74HCT devices are intended to interface be-
tween TTL and NMOS components and standard CMOS
devices. These parts are also plug in replacements for LS-
TTL devices and can be used to reduce power consumption
in existing designs.
All inputs are protected from damage due to static dis-
charge by diodes to V
CC
and ground.
Features
Y
TTL input compatible
Y
Typical propagation delay: 20 ns
Y
Low quiescent current: 80
m
A maximum (74HCT Series)
Y
Large output current: 4 mA
Y
Same as HCT521
Logic Diagrams
TL/F/5371±2
C
1995 National Semiconductor Corporation
TL/F/5371
RRD-B30M105/Printed in U. S. A.
Absolute Maximum Ratings
(Notes1&2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage (V
CC
)
Operating Condition
Min Max Units
Supply Voltage (V
CC
)
4.5
5.5
V
DC Input or Output Voltage
0
V
CC
V
b
0.5 to
a
7.0V
(V
IN
,V
OUT
)
Operating Temp. Range (T
A
)
MM74HCT688
DC Input Voltage (V
IN
)
b
1.5 to V
CC
a
1.5V
DC Output Voltage (V
OUT
)
b
0.5 to V
CC
a
0.5V
b
40
a
85
§
C
MM54HCT688
b
55
a
125
§
C
Clamp Diode Current (I
IK
,I
OK
)
g
20 mA
Input Rise or Fall Times
(t
r
,t
f
)
g
25 mA
DC V
CC
or GND Current, per pin (I
CC
)
g
50 mA
Storage Temperature Range (T
STG
)
b
65
§
Cto
a
150
§
C
Power Dissipation (P
D
)
(Note 3)
500
ns
600 mW
S.O. Package only
500 mW
Lead Temperature (T
L
)
(Soldering 10 seconds)
260
§
C
DC Electrical Characteristics
(V
CC
e
5V
g
10% unless otherwise specified)
T
A
e
25
§
C
74HCT
54HCT
Symbol
Parameter
Conditions
T
A
eb
40 to 85
§
CT
A
eb
55 to 125
§
C
Units
Typ
Guaranteed Limits
V
IH
Minimum High Level
2.0
2.0
2.0
V
Input Voltage
V
IL
Maximum Low Level
0.8
0.8
0.8
V
Input Voltage
V
OH
Minimum High Level V
IN
e
0.8V or 2.0V
Output Voltage
l
I
OUT
l
e
20
m
A
V
CC
V
CC
b
0.1 V
CC
b
0.1
V
CC
b
0.1
V
l
I
OUT
l
e
4.0 mA, V
CC
e
4.5V 4.2 3.98
3.84
3.7
V
l
I
OUT
l
e
4.8 mA, V
CC
e
5.5V 5.7 4.98
4.84
4.7
V
V
OL
Maximum Low Level V
IN
e
V0.8V or 2.0V
Voltage
l
I
OUT
l
e
20
m
A
0
0.1
0.1
0.1
V
l
I
OUT
l
e
4.0 mA, V
CC
e
4.5V 0.2 0.26
0.33
0.4
V
l
I
OUT
l
e
4.8 mA, V
CC
e
5.5V 0.2 0.26
0.33
0.4
V
I
IN
Maximum Input
V
IN
e
V
CC
or GND
g
0.1
g
1.0
g
1.0
m
A
Current
I
CC
Maximum Quiescent V
IN
e
V
CC
or GND
8.0
80
160
m
A
Supply Current
I
OUT
e
0
m
A
V
IN
e
2.4V or 0.5V (Note 4)
0.3
0.4
0.5
mA
Note 1: Absolute Maximum Ratings are those values beyond which damage to the device may occur.
Note 2: Unless otherwise specified all voltages are referenced to ground.
Note 3: Power Dissipation temperature derating Ð plastic ``N'' package:
b
12 mW/
§
C from 65
§
Cto85
§
C; ceramic ``J'' package:
b
12 mW/
§
C from 100
§
Cto125
§
C.
Note 4: Measured per pin. All other inputs held at V
CC
or ground.
2
DC Output Current, per pin (I
OUT
)
AC Electrical Characteristics
V
CC
e
5V, T
A
e
25
§
C, C
L
e
15 pF, t
r
e
t
f
e
6 ns (unless otherwise specified)
Symbol
Parameter
Conditions Typ
Guaranteed
Units
Limit
t
PHL
Maximum Propagation
19
30
ns
Delay-PorQtoOutput
t
PLH
Maximum Propagation
13
22
ns
Delay-PorQtoOutput
t
PHL
Maximum Propagation
13
20
ns
Delay - Enable to Output
t
PHL
Maximum Propagation
10
18
ns
Delay - Enable to Output
AC Electrical Characteristics
V
CC
e
5V
g
10%, C
L
e
50 pF, t
r
e
t
f
e
6 ns (unless otherwise specified)
T
A
e
25
§
C
74HCT
54HCT
Symbol
Parameter
Conditions
T
A
eb
40 to 85
§
C
eb
55 to 125
§
C
Units
Typ
Guaranteed Limits
t
PHL
Maximum Propagation
23 35
44
53
ns
Delay-PorQtoOutput
t
PLH
Maximum Propagation
16 24
30
36
ns
Delay-PorQtoOutput
t
PHL
Maximum Propagation
16 24
30
36
ns
Delay - Enable to Output
t
PLH
Maximum Propagation
11 20
25
30
ns
Delay - Enable to Output
t
THL
,t
TLH
Maximum Output Rise
8
15
19
22
ns
and Fall Time
C
PD
Power Dissipation
45
pF
Capacitance (Note 5)
C
IN
Maximum Input
5
10
10
10
pF
Capacitance
Note 5: C
PD
determines the no load dynamic power consumption, P
D
e
C
PD
V
CC
2
f
a
I
CC
V
CC
, and the no load dynamic current consumption,
I
S
e
C
PD
V
CC
a
I
CC
.
Connection Diagram
Dual-In-Line Package
Truth Table
Inputs
Data
En
ab
le P
e
Q
P, Q
G
P
e
Q
L
L
P
l
Q
L
H
P
k
Q
L
H
X
H
H
TL/F/5371±1
Top View
Order Number MM54HCT688 or MM74HCT688
3
Physical Dimensions
inches (millimeters)
Order Number MM54HCT688J or MM74HCT688J
NS Package J20A
LIFE SUPPORT POLICY
Order Number MM74HCT688N
NS Package N20A
NATIONAL'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 NATIONAL
SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or 2. A critical component is any component of a life
systems which, (a) are intended for surgical implant
support device or system whose failure to perform can
into the body, or (b) support or sustain life, and whose
be reasonably expected to cause the failure of the life
failure to perform, when properly used in accordance
support device or system, or to affect its safety or
with instructions for use provided in the labeling, can
effectiveness.
be reasonably expected to result in a significant injury
to the user.
National Semiconductor
National Semiconductor
National Semiconductor
National Semiconductor
Corporation
Europe
Hong Kong Ltd.
Japan Ltd.
1111 West Bardin Road
Fax: (
a
49) 0-180-530 85 86
13th Floor, Straight Block,
Tel: 81-043-299-2309
Arlington, TX 76017
Email: cnjwge
@
tevm2.nsc.com
Ocean Centre, 5 Canton Rd.
Fax: 81-043-299-2408
Tel: 1(800) 272-9959
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a
49) 0-180-530 85 85
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Fax: 1(800) 737-7018
English Tel: (
a
49) 0-180-532 78 32
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3
ais Tel: (
a
49) 0-180-532 93 58
Tel: (852) 2737-1600
Italiano Tel: (
a
49) 0-180-534 16 80
Fax: (852) 2736-9960
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
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