SN74HC148D [TI]
8-LINE TO 3-LINE PRIORITY ENCODERS; 8号线到3线优先编码器
| 型号： | SN74HC148D |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 8-LINE TO 3-LINE PRIORITY ENCODERS |
| 文件： | 总8页 (文件大小：129K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SN54HC148, SN74HC148
8-LINE TO 3-LINE PRIORITY ENCODERS
SCLS109D – MARCH 1984 – REVISED MAY 1997
SN54HC148 . . . J OR W PACKAGE
SN74HC148 . . . D OR N PACKAGE
(TOP VIEW)
Encode Eight Data Lines to 3-Line Binary
(Octal)
Applications Include:
– n-Bit Encoding
– Code Converters and Generators
4
5
V
CC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
EO
GS
3
Package Options Include Plastic
Small-Outline (D) and Ceramic Flat (W)
Packages, Ceramic Chip Carriers (FK), and
Standard Plastic (N) and Ceramic (J)
300-mil DIPs
6
7
EI
2
A2
A1
GND
1
0
A0
description
The ’HC148 feature priority decoding of the inputs
to ensure that only the highest-order data line is
encoded. These devices encode eight data lines
to 3-line (4-2-1) binary (octal). Cascading circuitry
(enable input EI and enable output EO) has been
provided to allow octal expansion without the
needforexternalcircuitry. Datainputsandoutputs
are active at the low logic level.
SN54HC148 . . . FK PACKAGE
(TOP VIEW)
3
2
1
20 19
18
GS
3
6
7
4
5
6
7
8
17
16
15
14
NC
2
NC
EI
The SN54HC148 is characterized for operation
over the full military temperature range of –55°C
to 125°C. The SN74HC148 is characterized for
operation from –40°C to 85°C.
1
A2
9 10 11 12 13
NC – No internal connection
FUNCTION TABLE
INPUTS
OUTPUTS
EI
H
L
0
X
H
X
X
X
X
X
X
1
X
H
X
X
X
X
X
X
2
X
H
X
X
X
X
X
L
3
X
H
X
X
X
X
L
4
X
H
X
X
X
L
5
X
H
X
X
L
6
X
H
X
L
7
X
H
L
A2
H
H
L
A1
H
H
L
A0
H
H
L
GS
H
H
L
EO
H
L
L
H
H
H
H
H
H
L
H
H
H
H
H
L
L
H
L
L
L
H
H
H
H
L
H
H
L
L
L
H
H
H
L
H
L
L
L
H
H
H
H
L
L
H
L
H
L
L
L
X
L
L
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
L
L
L
H
H
H
H
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.
Copyright 1997, Texas Instruments Incorporated
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.
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54HC148, SN74HC148
8-LINE TO 3-LINE PRIORITY ENCODERS
SCLS109D – MARCH 1984 – REVISED MAY 1997
†
logic symbol
HPRI/BIN
10
≥1
0
10
11
12
13
14
15
16
17
0/Z10
1/Z11
2/Z12
3/Z13
4/Z14
5/Z15
6/Z16
7/Z17
11
12
13
1
1
2
3
4
5
6
15
14
EO
GS
18
2
3
4
7
9
7
6
A0
A1
A2
1
2
4
V18
EN
5
EI
†
This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
Pin numbers shown are for the D, J, N, and W packages.
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54HC148, SN74HC148
8-LINE TO 3-LINE PRIORITY ENCODERS
SCLS109D – MARCH 1984 – REVISED MAY 1997
logic diagram (positive logic)
10
0
15
EO
14
GS
11
1
12
2
9
A0
13
3
1
4
7
A1
2
5
3
6
4
7
6
A2
5
EI
Pin numbers shown are for the D, J, N, and W packages.
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54HC148, SN74HC148
8-LINE TO 3-LINE PRIORITY ENCODERS
SCLS109D – MARCH 1984 – REVISED MAY 1997
†
absolute maximum ratings over operating free-air temperature range
Supply voltage range, V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to 7 V
CC
I
Input clamp current, I (V < 0 or V > V ) (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±20 mA
IK
I
CC
Output clamp current, I
(V < 0 or V > V ) (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±20 mA
OK
O O CC
Continuous output current, I (V = 0 to V ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±25 mA
Continuous current through V
Package thermal impedance, θ (see Note 2): D package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113°C/W
O
O
CC
CC
or GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±50 mA
JA
N package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78°C/W
Storage temperature range, T
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C
stg
†
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.
recommended operating conditions
SN54HC148
MIN NOM
SN74HC148
MIN NOM
UNIT
MAX
MAX
V
V
Supply voltage
2
1.5
3.15
4.2
0
5
6
2
1.5
3.15
4.2
0
5
6
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
= 2 V
High-level input voltage
= 4.5 V
= 6 V
V
V
IH
= 2 V
0.5
1.35
1.8
0.5
1.35
1.8
V
IL
Low-level input voltage
= 4.5 V
= 6 V
0
0
0
0
V
V
Input voltage
0
V
V
0
V
V
V
V
I
CC
CC
Output voltage
0
0
O
CC
CC
V
CC
V
CC
V
CC
= 2 V
0
1000
500
400
125
0
1000
500
400
85
t
Input transition (rise and fall) time
Operating free-air temperature
= 4.5 V
= 6 V
0
0
ns
t
0
0
T
–55
–40
°C
A
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54HC148, SN74HC148
8-LINE TO 3-LINE PRIORITY ENCODERS
SCLS109D – MARCH 1984 – REVISED MAY 1997
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
T
= 25°C
SN54HC148
SN74HC148
A
PARAMETER
TEST CONDITIONS
V
UNIT
CC
MIN
TYP
MAX
MIN
1.9
4.4
5.9
3.7
5.2
MAX
MIN
1.9
MAX
2 V
4.5 V
6 V
1.9 1.998
4.4 4.499
5.9 5.999
I
= –20 µA
4.4
OH
V
V = V or V
IH
5.9
V
OH
OL
I
IL
IL
I
I
= –4 mA
4.5 V
6 V
3.98
5.48
4.3
5.8
3.84
5.34
OH
= –5.2 mA
OH
2 V
0.002
0.001
0.001
0.17
0.1
0.1
0.1
0.1
0.1
0.1
I
= 20 µA
4.5 V
6 V
OL
V
V = V or V
0.1
0.1
0.1
V
I
IH
I
I
= 4 mA
4.5 V
6 V
0.26
0.26
±100
8
0.4
0.33
0.33
±1000
80
OL
= 5.2 mA
0.15
0.4
OL
I
I
V = V
I
or 0
6 V
±0.1
±1000
160
10
nA
µA
pF
I
CC
CC
V = V
I
or 0,
I
O
= 0
6 V
CC
C
2 V to 6 V
3
10
10
i
switching characteristics over recommended operating free-air temperature range, C = 50 pF
L
(unless otherwise noted) (see Figure 1)
T
A
= 25°C
TYP
69
23
21
60
20
17
75
25
21
78
26
22
57
19
16
66
22
19
28
8
SN54HC148
SN74HC148
FROM
(INPUT)
TO
(OUTPUT)
PARAMETER
V
UNIT
CC
MIN
MAX
180
36
MIN
MAX
270
54
MIN
MAX
225
45
2 V
4.5 V
6 V
1–7
0–7
A0, A1, or A2
31
46
38
2 V
150
30
225
45
190
38
EO
GS
4.5 V
6 V
26
38
33
2 V
190
38
285
57
240
48
4.5 V
6 V
32
48
41
t
pd
ns
2 V
195
39
295
59
245
49
A0, A1, or A2
GS
4.5 V
6 V
33
50
42
2 V
145
29
220
44
180
36
EI
4.5 V
6 V
25
38
31
2 V
165
33
250
50
205
41
EO
4.5 V
6 V
28
43
35
2 V
75
110
22
95
t
t
Any
4.5 V
6 V
15
19
ns
6
13
19
16
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54HC148, SN74HC148
8-LINE TO 3-LINE PRIORITY ENCODERS
SCLS109D – MARCH 1984 – REVISED MAY 1997
operating characteristics, T = 25°C
A
PARAMETER
TEST CONDITIONS
TYP
UNIT
C
Power dissipation capacitance
No load
35
pF
pd
PARAMETER MEASUREMENT INFORMATION
V
CC
From Output
Under Test
Test
Point
Input
50%
50%
0 V
C
= 50 pF
L
t
t
PLH
PHL
90%
(see Note A)
V
V
OH
In-Phase
Output
90%
t
50%
10%
50%
10%
LOAD CIRCUIT
OL
t
r
f
f
t
t
PLH
PHL
90%
V
CC
V
V
90%
t
90%
OH
Input
50%
10%
50%
10%
90%
t
Out-of-Phase
Output
50%
10%
50%
10%
0 V
OL
t
r
f
t
r
VOLTAGE WAVEFORM
INPUT RISE AND FALL TIMES
VOLTAGE WAVEFORMS
PROPAGATION DELAY AND OUTPUT TRANSITION TIMES
NOTES: A.
B. Phase relationships between waveforms were chosen arbitrarily. All input pulses are supplied by generators having the following
characteristics: PRR ≤ 1 MHz, Z = 50 Ω, t = 6 ns, t = 6 ns.
C includes probe and test-fixture capacitance.
L
O
r
f
C. The outputs are measured one at a time with one input transition per measurement.
D. and t are the same as t
t
.
pd
PLH
PHL
Figure 1. Load Circuit and Voltage Waveforms
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN54HC148, SN74HC148
8-LINE TO 3-LINE PRIORITY ENCODERS
SCLS109D – MARCH 1984 – REVISED MAY 1997
APPLICATION INFORMATION
16-Line Data (active low)
0
0
1
1
2
2
3
3
4
4
5
5
6
6
7
8
8
0
9 10 11 12 13 14 15
Enable
(active low)
7 EI
1
2
3
4
5
6
7 EI
GS
’HC148
A1
’HC148
A1
EO A0
A2 GS
EO
A0
A2
’HC08
Priority Flag
(active low)
0
1
2
3
Encoded Data (active low)
16-Line Data (active low)
0
0
1
1
2
2
3
4
5
6
6
7
8
8
0
9 10 11 12 13 14 15
Enable
(active low)
3
4
5
7 EI
1
2
3
4
5
6
7 EI
GS
’HC148
A1
’HC148
A1
EO A0
A2 GS
EO
A0
A2
’HC00
Priority Flag
(active high)
0
1
2
3
Encoded Data (active high)
Figure 2. Priority Encoder for 16 Bits
Since the ’HC148 is a combinational logic circuit, wrong addresses can appear during input transients. Moreover, a
change from high to low at EI can cause a transient low on GS when all inputs are high. This must be considered when
strobing the outputs.
7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
IMPORTANT NOTICE
Texas 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.
CERTAIN 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 APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD 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 1998, Texas Instruments Incorporated
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TI
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