Texas Instruments SN74ALS639ADW, SN74ALS639ADWR, SN74ALS639AN, SN74ALS638A-1DW, SN74ALS638A-1DWR Datasheet
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SN74ALS638A, SN74ALS639A, SN74AS638A, SN74AS639
OCTAL BUS TRANSCEIVERS
SDAS123A – DECEMBER 1983 – REVISED JANUARY 1995
Copyright 1995, Texas Instruments Incorporated
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
• Bidirectional Bus Transceivers in
High-Density 20-Pin Packages
• Choice of True or Inverting Logic
• A-Bus Outputs Are Open Collector;
B-Bus Outputs Are 3 State
• Package Options Include Plastic
Small-Outline (DW) Packages and
Standard Plastic (N) 300-mil DIPs
DEVICE
A
OUTPUTBOUTPUT
LOGIC
SN74ALS638A, SN74AS638A Open collector 3 state Inverting
SN74ALS639A, SN74AS639 Open collector 3 state True
description
These octal bus transceivers are designed for asynchronous two-way communication between open-collector
and 3-state buses. The devices transmit data from the A bus (open-collector) to the B bus (3 state) or from the
B bus to the A bus, depending on the logic level at the direction-control (DIR) input. The output-enable (OE
) input
can be used to disable the device so the buses are isolated.
The -1 version of SN74ALS638A is identical to the standard version, except that the recommended maximum
I
OL
is increased to 48 mA.
The SN74ALS638A, SN74ALS639A, SN74AS638A, and SN74AS639 are characterized for operation from 0°C
to 70°C.
FUNCTION TABLE
INPUTS
OPERATION
OE DIR
SN74ALS638A
SN74AS638A
SN74ALS639A
SN74AS639
L L B data to A bus B data to A bus
L HA data to B bus A data to B bus
H X Isolation Isolation
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
DIR
A1
A2
A3
A4
A5
A6
A7
A8
GND
V
CC
OE
B1
B2
B3
B4
B5
B6
B7
B8
DW OR N PACKAGE
(TOP VIEW)
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.
SN74ALS638A, SN74ALS639A, SN74AS638A, SN74AS639
OCTAL BUS TRANSCEIVERS
SDAS123A – DECEMBER 1983 – REVISED JANUAR Y 1995
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
logic symbols
†
B2
17
B3
16
B4
15
A5
6
A6
7
A7
8
A8
9
A2
3
A3
4
A4
5
OE
A1
2
G3
19
3 EN2 [AB]
B5
14
B6
13
B7
12
B8
11
B1
18
3 EN1 [BA]
1
DIR
1
2
B2
17
B3
16
B4
15
A5
6
A6
7
A7
8
A8
9
A2
3
A3
4
A4
5
OE
A1
2
G3
19
3 EN2 [AB]
B5
14
B6
13
B7
12
B8
11
B1
18
3 EN1 [BA]
1
DIR
1
2
SN74ALS638A, SN74AS638A SN74ALS639A, SN74AS639
†
These symbols are in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
logic diagrams (positive logic)
SN74ALS638A, SN74AS638A SN74ALS639A, SN74AS639
To Seven Other Transceivers
OE
A1
DIR
B1
19
2
1
18
To Seven Other Transceivers
OE
A1
DIR
B1
19
2
1
18
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
‡
Supply voltage, V
CC
7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input voltage, V
I
: All inputs 7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A-bus I/O ports 7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B-bus I/O ports 5.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, T
A
: SN74ALS638A, SN74ALS639A 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.
SN74ALS638A, SN74ALS639A, SN74AS638A, SN74AS639
OCTAL BUS TRANSCEIVERS
SDAS123A – DECEMBER 1983 – REVISED JANUARY 1995
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
recommended operating conditions
SN74ALS638A
SN74ALS639A
UNIT
MIN NOM MAX
V
CC
Supply voltage 4.5 5 5.5 V
V
IH
High-level input voltage 2 V
V
IL
Low-level input voltage 0.8 V
V
OH
High-level output voltage A ports 5.5 V
I
OH
High-level output current B ports –15 mA
p
p
24
IOLLow-level output current
A or B ports
48
†
mA
T
A
Operating free-air temperature 0 70 °C
†
Applies only to the SN74ALS638A-1 version and only if VCC is between 4.75 V and 5.25 V
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER TEST CONDITIONS
SN74ALS638A
SN74ALS639A
UNIT
MIN TYP‡MAX
V
IK
VCC = 4.5 V, II = –18 mA –1.5 V
I
OH
A ports VCC = 4.5 V, VOH = 5.5 V 0.1 mA
VCC = 4.5 V to 5.5 V, IOH = –0.4 mA VCC –2
V
OH
B ports
IOH = –3 mA 2.4 3.2
V
V
CC
=
4.5 V
IOH = –15 mA 2
IOL = 12 mA 0.25 0.4
V
OL
A or B ports VCC = 4.5 V
IOL = 24 mA 0.35 0.5
V
IOL = 48 mA
†
0.35 0.5
Control inputs
VI = 7 V 0.1
I
I
A or B ports
V
CC
= 5.5
V
VI = 5.5 V 0.1
mA
Control inputs
20
I
IH
A or B ports
§
V
CC
=
5.5 V
,
V
I
=
2.7 V
20
µ
A
Control inputs
–0.1
I
IL
A or B ports
§
V
CC
= 5.5 V,
V
I
= 0.4
V
–0.1
mA
I
O
¶
B ports VCC = 5.5 V, VO = 2.25 V –30 –112 mA
Outputs high 18 30
SN74ALS638A VCC = 5.5 V
Outputs low 26 41
Outputs disabled 16 30
I
CC
Outputs high 25 40
mA
SN74ALS639A VCC = 5.5 V
Outputs low 30 50
Outputs disabled 33 54
†
Applies only to the SN74ALS638A-1 version and only if VCC is between 4.75 V and 5.25 V
‡
All typical values are at VCC = 5 V, TA = 25°C.
§
For I/O ports, the parameters IIH and IIL include the off-state output current.
¶
The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, IOS.
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