SN54ALS688, SN74ALS688
8-BIT IDENTITY COMPARATORS
SDAS228A JUNE 1982 REVISED JANUARY 1995
Copyright
1995, Texas Instruments Incorporated
1
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
Compare Two 8-Bit Words
Totem-Pole Outputs (P = Q)
ALS688 Are Identical to
ALS521
Package Options Include Plastic
Small-Outline (DW) Packages, Ceramic
Chip Carriers (FK), and Standard Plastic (N)
and Ceramic (J) 300-mil DIPs
description
These identity comparators perform comparisons
on two 8-bit binary or BCD words and provide
P = Q outputs. These devices have totem-pole
outputs.
The SN54ALS688 is characterized for operation
over the full military temperature range of 55
C
to 125
C. The SN74ALS688 is characterized for
operation from 0
C to 70
C.
FUNCTION TABLE
INPUTS
OUTPUT
DATA
P, Q
ENABLE
G
OUTPUT
P = Q
P = Q
L
L
P > Q
L
H
P < Q
L
H
X
H
H
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
G
P0
Q0
P1
Q1
P2
Q2
P3
Q3
GND
V
CC
P = Q
Q7
P7
Q6
P6
Q5
P5
Q4
P4
SN54ALS688 . . . J PACKAGE
SN74ALS688 . . . DW OR N PACKAGE
(TOP VIEW)
3
2 1 20 19
9 10 11 12 13
4
5
6
7
8
18
17
16
15
14
Q7
P7
Q6
P6
Q5
P1
Q1
P2
Q2
P3
SN54ALS688 . . . FK PACKAGE
(TOP VIEW)
Q0
P0
G
Q4
P5
P
= Q
Q3
GND
P4
V
CC
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
SN54ALS688, SN74ALS688
8-BIT IDENTITY COMPARATORS
SDAS228A JUNE 1982 REVISED JANUARY 1995
2
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
logic symbol
COMP
G1
1
0
2
P0
4
P1
6
P2
8
P3
11
P4
13
P5
15
P6
7
17
P7
0
3
Q0
5
Q1
7
Q2
9
Q3
12
Q4
14
Q5
16
Q6
7
18
Q7
19
1P=Q
G
P
Q
P = Q
This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
SN54ALS688, SN74ALS688
8-BIT IDENTITY COMPARATORS
SDAS228A JUNE 1982 REVISED JANUARY 1995
3
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
logic diagram (positive logic)
19
17
18
15
16
13
14
11
12
8
9
6
7
4
5
2
3
1
P = Q
P7
Q7
P6
Q6
P5
Q5
P4
Q4
P3
Q3
P2
Q2
P1
Q1
P0
Q0
G
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage, V
CC
7 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input voltage, V
I
7 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, T
A
: SN54ALS688
55
C to 125
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SN74ALS688
0
C to 70
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range
65
C to 150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
SN54ALS688, SN74ALS688
8-BIT IDENTITY COMPARATORS
SDAS228A JUNE 1982 REVISED JANUARY 1995
4
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
recommended operating conditions
SN54ALS688
SN74ALS688
UNIT
MIN
NOM
MAX
MIN
NOM
MAX
UNIT
VCC
Supply voltage
4.5
5
5.5
4.5
5
5.5
V
VIH
High-level input voltage
2
2
V
VIL
Low-level input voltage
0.7
0.8
V
IOH
High-level output current
1
2.6
mA
IOL
Low-level output current
12
24
mA
TA
Operating free-air temperature
55
125
0
70
C
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
SN54ALS688
SN74ALS688
UNIT
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNIT
VIK
VCC = 4.5 V,
II = 18 mA
1.5
1.5
V
VCC = 4.5 V to 5.5 V,
IOH = 0.4 mA
VCC 2
VCC 2
VOH
VCC = 4 5 V
IOH = 1 mA
2.4
3.3
V
VCC = 4.5 V
IOH = 2.6 mA
2.4
3.3
VOL
VCC = 4 5 V
IOL = 12 mA
0.25
0.4
0.25
0.4
V
VOL
VCC = 4.5 V
IOL = 24 mA
0.35
0.5
V
II
VCC = 5.5 V,
VI = 7 V
0.1
0.1
mA
IIH
VCC = 5.5 V,
VI = 2.7 V
20
20
A
IIL
VCC = 5.5 V,
VI = 0.4 V
0.1
0.1
mA
IO
VCC = 5.5 V,
VO = 2.25 V
20
112
30
112
mA
ICC
VCC = 5.5 V,
See Note 1
12
19
12
19
mA
All typical values are at VCC = 5 V, TA = 25
C.
The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, IOS.
NOTE 1: ICC is measured with G grounded, P and Q at 4.5 V.
switching characteristics (see Figure 1)
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
VCC = 4.5 V to 5.5 V,
CL = 50 pF,
RL = 500
,
TA = MIN to MAX
UNIT
(INPUT)
(OUTPUT)
SN54ALS688
SN74ALS688
MIN
MAX
MIN
MAX
tPLH
P
P
Q
3
16
3
12
ns
tPHL
P
P = Q
5
25
5
20
ns
tPLH
Q
P
Q
3
16
3
12
ns
tPHL
Q
P = Q
5
25
5
20
ns
tPLH
G
P = Q
3
15
3
12
ns
tPHL
G
P = Q
5
25
5
22
ns
For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.
SN54ALS688, SN74ALS688
8-BIT IDENTITY COMPARATORS
SDAS228A JUNE 1982 REVISED JANUARY 1995
5
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
SERIES 54ALS/ 74ALS AND 54AS/ 74AS DEVICES
tPHZ
tPLZ
tPHL
tPLH
0.3 V
tPZL
tPZH
tPLH
tPHL
LOAD CIRCUIT
FOR 3-STATE OUTPUTS
From Output
Under Test
Test
Point
R1
S1
CL
(see Note A)
7 V
1.3 V
1.3 V
1.3 V
3.5 V
3.5 V
0.3 V
0.3 V
th
tsu
VOLTAGE WAVEFORMS
SETUP AND HOLD TIMES
Timing
Input
Data
Input
1.3 V
1.3 V
3.5 V
3.5 V
0.3 V
0.3 V
High-Level
Pulse
Low-Level
Pulse
tw
VOLTAGE WAVEFORMS
PULSE DURATIONS
Input
Out-of-Phase
Output
(see Note C)
1.3 V
1.3 V
1.3 V
1.3 V
1.3 V
1.3 V
1.3 V
1.3 V
1.3 V
1.3 V
3.5 V
3.5 V
0.3 V
0.3 V
VOL
VOH
VOH
VOL
Output
Control
(low-level
enabling)
Waveform 1
S1 Closed
(see Note B)
Waveform 2
S1 Open
(see Note B)
[
0 V
VOH
VOL
[
3.5 V
In-Phase
Output
0.3 V
1.3 V
1.3 V
VOLTAGE WAVEFORMS
PROPAGATION DELAY TIMES
VOLTAGE WAVEFORMS
ENABLE AND DISABLE TIMES, 3-STATE OUTPUTS
R2
VCC
RL
Test
Point
From Output
Under Test
CL
(see Note A)
LOAD CIRCUIT
FOR OPEN-COLLECTOR OUTPUTS
LOAD CIRCUIT FOR
BI-STATE
TOTEM-POLE OUTPUTS
From Output
Under Test
Test
Point
CL
(see Note A)
RL
RL = R1 = R2
NOTES: A. CL includes probe and jig capacitance.
B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control.
Waveform 2 is for an output with internal conditions such that the output is high except when disabled by the output control.
C. When measuring propagation delay items of 3-state outputs, switch S1 is open.
D. All input pulses have the following characteristics: PRR
1 MHz, tr = tf = 2 ns, duty cycle = 50%.
E. The outputs are measured one at a time with one transition per measurement.
Figure 1. Load Circuits and Voltage Waveforms
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