OE
Y
SN54HCT257, SN74HCT257
QUADRUPLE 2-LINE TO 1-LINE DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS072B – NOVEMBER 1988 – REVISED MA Y 1997
D
Inputs Are TTL-Voltage Compatible
D
Provide Bus Interface From Multiple
Sources in High-Performance Systems
D
High-Current 3-State Outputs Interface
Directly With System Bus
D
Buffered Inputs and Outputs
D
Package Options Include Ceramic Chip
Carriers (FK) and Standard Plastic (N) and
Ceramic (J) 300-mil DIPs
description
The ’HCT257 are designed to multiplex signals
from 4-bit data sources to 4-output data lines in
bus-organized systems. The 3-state outputs do
not load the data lines when the output-enable
(OE) input is at the high logic level.
The SN54HCT257 is characterized for operation
over the full military temperature range of –55°C
to 125°C. The SN74HCT257 is characterized for
operation from –40°C to 85°C.
FUNCTION TABLE
INPUTS
SELECT
A/B
H X X X Z
L L L XL
L L H XH
L H X LL
L H X H H
DATA
A B
OUTPUT
SN54HCT257 ...J PACKAGE
SN74HCT257 . . . N PACKAGE
SN54HCT257 . . . FK PACKAGE
1B
1Y
NC
2A
2B
NC – No internal connection
(TOP VIEW)
A/B
1
1A
2
1B
3
1Y
4
5
2A
6
2B
7
2Y
GND
8
(TOP VIEW)
1A
3212019
4
5
6
7
8
910111213
2Y
A/B
GND
NC
NC
16
15
14
13
12
11
10
9
V
3Y
CC
V
OE
4A
4B
4Y
3A
3B
3Y
OE
18
17
16
15
14
3B
CC
4A
4B
NC
4Y
3A
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
UNLESS OTHERWISE NOTED this document contains PRODUCTION
DATA information 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.
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Copyright 1997, Texas Instruments Incorporated
1
SN54HCT257, SN74HCT257
QUADRUPLE 2-LINE TO 1-LINE DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS072B – NOVEMBER 1988 – REVISED MA Y 1997
logic symbol
†
This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
Pin numbers shown are for the J and N packages.
†
15
OE
A/B
1A
1B
2A
2B
3A
3B
4A
4B
1
2
3
5
6
11
10
14
13
EN
G1
1
1
MUX
logic diagram (positive logic)
15
OE
1
A
/B
12
4
1Y
7
2Y
9
3Y
4Y
2
1A
3
1B
5
2A
6
2B
11
3A
10
3B
14
4A
13
4B
Pin numbers shown are for the J and N packages.
12
4
1Y
7
2Y
9
3Y
4Y
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
UNIT
PARAMETER
TEST CONDITIONS
V
UNIT
V
V
V
or V
4.5 V
V
V
V
V
V
4.5 V
V
SN54HCT257, SN74HCT257
QUADRUPLE 2-LINE TO 1-LINE DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS072B – NOVEMBER 1988 – REVISED MA Y 1997
absolute maximum ratings over operating free-air temperature range
Supply voltage range, V
–0.5 V to 7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CC
†
Input clamp current, IIK (VI < 0 or VI > VCC) (see Note 1) ±20 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output clamp current, IOK (VO < 0 or VO > VCC) (see Note 1) ±20 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous output current, IO (VO = 0 to VCC) ±35 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous current through VCC or GND ±70 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Package thermal impedance, θ
Storage temperature range, T
†
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.
NOTES: 1. The input and output voltage ratings may be exceeded if the input and output current ratings are observed.
2. The package thermal impedance is calculated in accordance with JESD 51, except for through-hole packages, which use a trace
length of zero.
(see Note 2): N package 78°C/W. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
JA
–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
stg
recommended operating conditions
SN54HCT257 SN74HCT257
MIN NOM MAX MIN NOM MAX
V
V
V
V
V
t
t
T
Supply voltage 4.5 5 5.5 4.5 5 5.5 V
CC
High-level input voltage VCC = 4.5 V to 5.5 V 2 2 V
IH
Low-level input voltage VCC = 4.5 V to 5.5 V 0 0.8 0 0.8 V
IL
Input voltage 0 V
I
Output voltage 0 V
O
Input transition (rise and fall) time 0 500 0 500 ns
Operating free-air temperature –55 125 –40 85 °C
A
CC
CC
0 V
0 V
CC
CC
V
V
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
CC
=
OH
OL
I
I
I
OZ
I
CC
‡
∆I
CC
C
i
* On products compliant to MIL-PRF-38535, this parameter is not production tested.
‡
This is the increase in supply current for each input that is at one of the specified TTL voltage levels rather than 0 V or VCC.
I
IH
=
or
I
IH
VI = VCC or 0 5.5 V ±0.1 ±100 ±1000 ±1000 nA
VO = VCC or 0, VI = VIH or V
VI = VCC or 0, IO = 0 5.5 V 8 160 80 µA
One input at 0.5 V or 2.4 V,
Other inputs at 0 or V
IL
IL
IOH = –20 µA
IOH = –6 mA
IOL = 20 µA
IOL = 6 mA
CC
IL
5.5 V ±0.01 ±0.5 ±10 ±5 µA
5.5 V 1.4 2.4 3 2.9 mA
4.5 V
to 5.5 V
TA = 25°C SN54HCT257 SN74HCT257
MIN TYP MAX MIN MAX MIN MAX
4.4 4.499 4.4 4.4
3.98 4.3 3.7 3.84
0.001 0.1 0.1 0.1
0.17 0.26 0.4 0.33
3 10 10* 10 pF
PRODUCT PREVIEW information concerns products in the formative or
design phase of development. Characteristic data and other
specifications are design goals. Texas Instruments reserves the right to
change or discontinue these products without notice.
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
3
SN54HCT257, SN74HCT257
PARAMETER
V
UNIT
A or B
Y
t
ns
A/B
Y
t
OE
Y
ns
t
OE
Y
ns
ttAn
ns
PARAMETER
V
UNIT
A or B
Y
t
ns
A/B
Y
t
OE
Y
ns
ttAn
ns
QUADRUPLE 2-LINE TO 1-LINE DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS072B – NOVEMBER 1988 – REVISED MA Y 1997
switching characteristics over recommended operating free-air temperature range, CL = 50 pF
(unless otherwise noted) (see Figure 1)
FROM TO
(INPUT) (OUTPUT)
pd
en
dis
y
CC
4.5 V 20 30 45 38
5.5 V 17 27 40 34
4.5 V 20 30 45 38
5.5 V 17 27 40 34
4.5 V 20 30 45 38
5.5 V 17 27 40 34
4.5 V 20 30 45 38
5.5 V 17 27 40 34
4.5 V 8 15 22 19
5.5 V 7 14 21 17
switching characteristics over recommended operating free-air temperature range, CL = 150 pF
(unless otherwise noted) (see Figure 1)
FROM TO
(INPUT) (OUTPUT)
pd
en
y
CC
4.5 V 22 38 57 48
5.5 V 19 35 53 44
4.5 V 22 38 57 48
5.5 V 19 35 53 44
4.5 V 23 40 60 50
5.5 V 20 38 57 48
4.5 V 17 42 63 53
5.5 V 14 38 57 48
TA = 25°C SN54HCT257 SN74HCT257
MIN TYP MAX MIN MAX MIN MAX
TA = 25°C SN54HCT257 SN74HCT257
MIN TYP MAX MIN MAX MIN MAX
operating characteristics, TA = 25°C
PARAMETER TEST CONDITIONS TYP UNIT
C
PRODUCT PREVIEW information concerns products in the formative or
design phase of development. Characteristic data and other
specifications are design goals. Texas Instruments reserves the right to
change or discontinue these products without notice.
Power dissipation capacitance No load 13 pF
pd
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54HCT257, SN74HCT257
QUADRUPLE 2-LINE TO 1-LINE DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS072B – NOVEMBER 1988 – REVISED MA Y 1997
PARAMETER MEASUREMENT INFORMATION
V
From Output
Under Test
(see Note A)
Test
Point
C
L
LOAD CIRCUIT
CC
S1
R
L
S2
PARAMETER C
t
t
PZH
t
PZL
t
PHZ
t
PLZ
t
en
t
dis
tpd or t
R
1 kΩ
1 kΩ
L
50 pF
150 pF
50 pF
50 pF
150 pF
L
or
Closed Open
Closed Open
or
S1
Open Closed
Open Closed
Open Open––
S2
Input
In-Phase
Output
Out-of-
Phase
Output
NOTES: A. CL includes probe and test-fixture capacitance.
C. Phase relationships between waveforms were chosen arbitrarily. All input pulses are supplied by generators having the following
D. The outputs are measured one at a time with one input transition per measurement.
E. t
G. t
1.3 V
t
PLH
90% 90%
t
PHL
1.3 V 1.3 V
10% 10%
OUTPUT AND 3-STATE BIDIRECTIONAL I/O
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.
characteristics: PRR ≤ 1 MHz, ZO = 50 Ω, tr = 6 ns, tf = 6 ns.
PLZ
F. t
PZL
PLH
VOLTAGE WAVEFORMS
PROPAGATION DELAY TIME
and t
and t
and t
are the same as t
PHZ
are the same as ten.
PZH
are the same as tpd.
PHL
1.3 V
t
PHL
t
r
t
PLH
t
f
.
dis
3 V
0 V
V
1.3 V1.3 V
OH
10%10%
V
OL
t
f
V
OH
90%90%
V
OL
t
r
Output
Control
(Low-Level
Enabling)
t
Output
Waveform 1
(See Note B)
t
PZH
Output
Waveform 2
(See Note B)
ENABLE AND DISABLE TIMES FOR 3-STATE OUTPUTS
1.3 V
PZL
VOLTAGE WAVEFORMS
1.3 V
1.3 V
1.3 V
t
PLZ
10%
90%
t
PHZ
3 V
0 V
≈ V
V
OL
V
OH
≈ 0 V
CC
Figure 1. Load Circuit and Voltage Waveforms
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
5
IMPORTANT NOTICE
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any product or service without notice, and advise customers to obtain the latest version of relevant information
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subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty . Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
CERTAIN APPLICATIONS USING SEMICONDUCT OR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL
APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
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Copyright 1998, Texas Instruments Incorporated
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