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PDF 74LS848 Data sheet ( Hoja de datos )
| Número de pieza | 74LS848 | |
| Descripción | 8-INPUT PRIORITY ENCODERS WITH 3-STATE OUTPUTS | |
| Fabricantes | Motorola Semiconductors | |
| Logotipo |  |
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8-INPUT PRIORITY ENCODERS
WITH 3-STATE OUTPUTS
The SN54 / 74LS348 and the SN54 / 74LS848 are eight input priority encod-
ers which provide the 8-line to 3-line function.
The outputs (A0 – A2) and inputs (0 – 7) are active low. The active low input
which has the highest priority (input 7 has the highest) is represented on the
outputs (output A0 is the lowest bit). An example would be if inputs 1, 2 and 4
were low, then a binary 4 would be represented on the outputs.
The GS (Group Signal) output is active low when any of the inputs are low. It
serves to indicate when any of the inputs are active.
A0, A1 and A2 are three-state outputs. This allows for up to 64 line expan-
sion without the need for special external circuitry.
A logical one on the Enable Input (EI) forces A0, A1 ared A2 to the disabled
state and outputs GS and EO to the high state. A high on all data inputs (0 – 7)
together with a low on the EI input disables outputs A0, A1, and A2 and forces
output GS to the high state and output EO to the low state.
Use of the EI input in conjunction with the EO output provides for the capa-
bility of having priority encoding of n input signals.
The LS848 has special internal circuitry providing for a greatly reduced neg-
ative going glitch on the GS (Group Signal) output and on a reduced tendency
for the A0, A1 and A2 outputs to become momentarily enabled. Both of these
occurrences happen when the EI input goes from a logical one to a logical zero
and all data inputs (0 – 7) are held at logical ones. The internal glitch reduction
circuitry does add an additional fan-in of one on all data inputs (compared to
that of the LS348).
OUTPUTS
VCC EO
16 15
GS
14
INPUTS
321
13 12 11
OUTPUT
0 A0
10 9
EO GS
4
56
3
7
21 0
A0
EI A2 A1
1 2 3 4 56 78
4 5 6 7 EI A2 A1 GND
INPUTS
OUTPUTS
SN54/74LS348
SN54/74LS848
8-INPUT PRIORITY ENCODERS
WITH 3-STATE OUTPUTS
LOW POWER SCHOTTKY
16
1
16
1
16
1
J SUFFIX
CERAMIC
CASE 620-09
N SUFFIX
PLASTIC
CASE 648-08
D SUFFIX
SOIC
CASE 751B-03
ORDERING INFORMATION
SN54LSXXXJ
SN74LSXXXN
SN74LSXXXD
Ceramic
Plastic
SOIC
FUNCTION TABLE
INPUTS
OUTPUTS
EI 0 1 2 3 4 5 6 7 A2 A1 A0 GS EO
H XXXXXXXX Z Z Z H H
L HHHHHHHH Z Z Z H L
L XXXXXXXL L L L L H
L XXXXXXLH L L H L H
L XXXXX LHH L H L L H
L XXXX LHHH L H H L H
L XXX LHHHH H L L L H
L XX LHHHHH H L H L H
L X LHHHHHH H H L L H
L LHHHHHHH H H H L H
FAST AND LS TTL DATA
5-499
H = HIGH Logic Level
L = LOW Logic Level
X = Irrelevant
Z = High Impedance State
1 page  
Case 751B-03 D Suffix
16-Pin Plastic
SO-16
-A-
16 9
-B-
P 0.25 (0.010) M
BM
1
8 PL
8
G
-T-
D16 PL
0.25 (0.010) M T B S
AS
C
SEATING
PLANE
K
R X 45°
MF
J
Case 648-08 N Suffix
16-Pin Plastic
-A-
16 9
B
18
F
C
S
-T-
SEATING
PLANE
L
H
G
D 16 PL
K
0.25 (0.010) M T A M
J
M
Case 620-09 J Suffix
-A- 16-Pin Ceramic Dual In-Line
16 9
-B-
18
CL
-T-
SEATING
PLANE
F
E
G
D 16 PL
N
0.25 (0.010) M T A S
K
M
J 16 PL
0.25 (0.010) M T B S
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION A AND B DO NOT INCLUDE MOLD
PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)
PER SIDE.
5. 751BĆ01 IS OBSOLETE, NEW STANDARD
751BĆ03.
DIM
A
B
C
D
F
G
J
K
M
P
R
MILLIMETERS
MIN MAX
9.80
10.00
3.80
4.00
1.35
1.75
0.35
0.49
0.40
1.25
1.27 BSC
0.19
0.25
0.10
0°Ă
0.25
7°Ă
5.80
6.20
0.25
0.50
INCHES
MIN MAX
0.386
0.393
0.150
0.157
0.054
0.068
0.014
0.019
0.016
0.049
0.050 BSC
0.008
0.009
0.004
0°Ă
0.009
7°Ă
0.229
0.244
0.010
0.019
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L" TO CENTER OF LEADS WHEN
FORMED PARALLEL.
4. DIMENSION B" DOES NOT INCLUDE MOLD
FLASH.
5. ROUNDED CORNERS OPTIONAL.
6. 648Ć01 THRU Ć07 OBSOLETE, NEW STANDARD
648Ć08.
DIM
A
B
C
D
F
G
H
J
K
L
M
S
MILLIMETERS
MIN MAX
18.80
19.55
6.35
6.85
3.69
4.44
0.39
0.53
1.02
1.77
2.54 BSC
1.27 BSC
0.21
0.38
2.80
3.30
7.50
0°
7.74
10°
0.51
1.01
INCHES
MIN MAX
0.740
0.770
0.250
0.270
0.145
0.175
0.015
0.021
0.040
0.070
0.100 BSC
0.050 BSC
0.008
0.015
0.110
0.130
0.295
0°
0.305
10°
0.020
0.040
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEAD WHEN
FORMED PARALLEL.
4. DIM F MAY NARROW TO 0.76 (0.030) WHERE
THE LEAD ENTERS THE CERAMIC BODY.
5. 620Ć01 THRU Ć08 OBSOLETE, NEW STANDARD
620Ć09.
DIM
A
B
C
D
E
F
G
J
K
L
M
N
MILLIMETERS
MIN MAX
19.05 19.55
6.10
7.36
Ċ 4.19
0.39
0.53
1.27 BSC
1.40
1.77
2.54 BSC
0.23
0.27
Ċ 5.08
7.62 BSC
0° 15°
0.39
0.88
INCHES
MIN MAX
0.750
0.770
0.240
0.290
Ċ 0.165
0.015
0.021
0.050 BSC
0.055
0.070
0.100 BSC
0.009
0.011
Ċ 0.200
0.300 BSC
0° 15°
0.015
0.035
FAST AND LS TTL DATA
5-503
5 Page | ||
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| PDF Descargar | [ Datasheet 74LS848.PDF ] | |
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