High-Current 3-State Outputs Interface
Directly With System Bus or Can Drive up
to 15 LSTTL Loads
D
Perform Parallel-to-Serial Conversion
D
Complementary Outputs Provide True and
Inverted Data
D
Package Options Include Plastic
Small-Outline (D), Shrink Small-Outline
(DB), and Ceramic Flat (W) Packages,
Ceramic Chip Carriers (FK), and Standard
Plastic (N) and Ceramic (J) DIPs
description
These data selectors/multiplexers contain full
binary decoding to select 1-of-8 data sources and
feature strobe-controlled complementary 3-state
outputs.
The 3-state outputs can interface with and drive
data lines of bus-organized systems. With all but
one of the common outputs disabled (in the
high-impedance state), the low impedance of the
single enabled output drives the bus line to a high
or low logic level. Both outputs are controlled by
the output-enable (OE
disabled when OE
The SN54HC251 is characterized for operation
over the full military temperature range of –55°C
to 125°C. The SN74HC251 is characterized for
operation from –40°C to 85 °C.
) input. The outputs are
is high.
SN54HC251 ...J OR W PACKAGE
SN74HC251 . . . D, DB, OR N PACKAGE
SN54HC251 . . . FK PACKAGE
D1
D0
NC
Y
W
NC – No internal connection
(TOP VIEW)
D3
1
D2
2
D1
3
D0
4
Y
5
W
6
OE
7
GND
8
(TOP VIEW)
D2D3NC
3212019
4
5
6
7
8
910111213
OE
GND
NC
16
15
14
13
12
11
10
9
V
C
CC
V
D4
D5
D6
D7
A
B
C
D4
18
17
16
15
14
B
CC
D5
D6
NC
D7
A
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.
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.
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Copyright 1999, Texas Instruments Incorporated
On products compliant to MIL-PRF-38535, all parameters are tested
unless otherwise noted. On all other products, production
processing does not necessarily include testing of all parameters.
1
SN54HC251, SN74HC251
OE
Y
W
DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS132C – DECEMBER 1982 – REVISED FEBRUARY 1999
CBA
XXXHZZ
LLLLD0D0
LLHLD1D1
LHLLD2D2
LHHLD3D3
HLLLD4D4
HLHLD5D5
HHLLD6D6
HHHLD7D7
D0, D1 . . . D7 = the level of the respective D input
FUNCTION TABLE
INPUTS
SELECT
OUTPUTS
logic symbol
†
This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
Pin numbers shown are for the D, DB, J, N, and W packages.
†
OE
D0
D1
D2
D3
D4
D5
D6
D7
7
11
A
10
B
9
C
4
3
2
1
15
14
13
12
EN
0
2
0
1
2
3
4
5
6
7
MUX
G
0
7
5
Y
6
W
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
logic diagram (positive logic)
7
OE
11
A
10
B
9
C
4
D0
3
D1
SN54HC251, SN74HC251
DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS132C – DECEMBER 1982 – REVISED FEBRUARY 1999
TG
TG
2
D2
1
D3
15
D4
14
D5
13
D6
12
D7
Pin numbers shown are for the D, DB, J, N, and W packages.
TG
TG
TG
TG
TG
TG
5
Y
6
W
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
3
SN54HC251, SN74HC251
UNIT
DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS132C – DECEMBER 1982 – REVISED FEBRUARY 1999
absolute maximum ratings over operating free-air temperature range
Supply voltage range, V
Input clamp current, I
Output clamp current, I
Continuous output current, I
Continuous current through V
Package thermal impedance, θ
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.
switching characteristics over recommended operating free-air temperature range, CL = 50 pF
(unless otherwise noted) (see Figure 1)
FROMTO
(INPUT)(OUTPUT)
A, B, or CW or Y
pd
Any DW or Y
t
en
t
dis
t
t
OE
OE
W or Y
W or Y
W or Y
CC
2 V58205300256
4.5 V21416051
6 V19355144
2 V44195283244
4.5 V17395749
6 V15334841
2 V30145210181
4.5 V10294236
6 V9253631
2 V25195283244
4.5 V15395749
6 V14334841
2 V207511095
4.5 V8152219
6 V6131916
TA = 25°CSN54HC251SN74HC251
MINTYPMAXMINMAXMINMAX
ns
ns
ns
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
5
SN54HC251, SN74HC251
PARAMETER
V
UNIT
t
ns
DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS132C – DECEMBER 1982 – REVISED FEBRUARY 1999
switching characteristics over recommended operating free-air temperature range, CL = 150 pF
(unless otherwise noted) (see Figure 1)
FROMTO
(INPUT)(OUTPUT)
A, B, or CW or Y
pd
Any DW or Y
t
en
t
t
OE
W or Y
W or Y
operating characteristics, TA = 25°C
PARAMETERTEST CONDITIONSTYPUNIT
C
Power dissipation capacitanceNo load70pF
pd
CC
2 V72300450375
4.5 V25609075
6 V22527765
2 V59300450375
4.5 V21609075
6 V18527765
2 V50230340285
4.5 V17466857
6 V15405850
2 V45210315265
4.5 V17426353
6 V13365345
TA = 25°CSN54HC251SN74HC251
MINTYPMAXMINMAXMINMAX
ns
ns
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
50%
t
t
S1
S2
PHL
PLH
50%50%
10%10%
Test
From Output
Under Test
(see Note A)
Input
In-Phase
Output
Out-of-Phase
Output
PROPAGATION DELAY AND OUTPUT TRANSITION TIMES
Input
50%
INPUT RISE AND FALL TIMES
Point
C
L
LOAD CIRCUIT
t
PLH
50%
t
PHL
VOLTAGE WAVEFORMS
90%90%
t
r
VOLTAGE WAVEFORM
R
L
90%90%
t
r
50%50%
10%10%
t
f
SN54HC251, SN74HC251
DATA SELECTORS/MULTIPLEXERS
WITH 3-STATE OUTPUTS
SCLS132C – DECEMBER 1982 – REVISED FEBRUARY 1999
V
t
CC
f
V
0 V
50%
10%10%
90%90%
CC
V
CC
0 V
V
OH
V
OL
t
f
V
OH
V
OL
t
r
PARAMETERC
t
Output
Control
Output
Output
t
t
t
t
t
PZL
t
PZH
PZH
PZL
PHZ
PLZ
t
en
t
dis
tpd or t
(Low-Level
Enabling)
Waveform 1
(See Note B)
Waveform 2
(See Note B)
ENABLE AND DISABLE TIMES FOR 3-STATE OUTPUTS
R
L
1 kΩ
1 kΩ
50%
VOLTAGE WAVEFORMS
L
50 pF
or
150 pF
50 pF
50 pF
or
150 pF
≈ V
50%
50%
CC
S1
OpenClosed
ClosedOpen
OpenClosed
ClosedOpen
OpenOpen––
50%
t
PLZ
10%
90%
t
PHZ
S2
V
CC
0 V
≈ V
V
OL
V
OH
≈ 0 V
CC
NOTES: A. CL includes probe and test-fixture 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. Phase relationships between waveforms were chosen arbitrarily. All input pulses are supplied by generators having the following
characteristics: PRR ≤ 1 MHz, ZO = 50 Ω, tr = 6 ns, tf = 6 ns.
D. The outputs are measured one at a time with one input transition per measurement.
E. t
F. t
G. t
PLZ
PZL
PLH
and t
and t
and t
are the same as t
PHZ
are the same as ten.
PZH
are the same as tpd.
PHL
dis
.
Figure 1. Load Circuit and Voltage Waveforms
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
7
IMPORTANT NOTICE
T exas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
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.
CERT AIN APPLICATIONS USING SEMICONDUCTOR 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
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICA TIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERST OOD TO
BE FULLY AT THE CUSTOMER’S RISK.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI’s publication of information regarding any third
party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.
Copyright 1999, Texas Instruments Incorporated
Loading...
+ hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.