SN74LS348DG

Manufacturer Part NumberSN74LS348DG
ManufacturerON Semiconductor
SN74LS348DG datasheet
 


Specifications of SN74LS348DG

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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
V CC
EO
GS
3
2
16
15
14
13
12
EO
GS
3
2
4
5
6
7
1
2
3
4
4
5
6
7
INPUTS
INPUTS
EI
0 1 2 3 4 5 6 7
H
X X X X X X X X
L
H H H H H H H H
L
X X X X X X X L
L
X X X X X X L H
L
X X X X X L H H
L
X X X X L H H H
L
X X X L H H H H
L
X X L H H H H H
L
X L H H H H H H
L
L H H H H H H H
INPUTS
OUTPUT
1
0
A0
11
10
9
1
0
A0
EI
A2
A1
5
6
8
7
EI
A2
A1
GND
OUTPUTS
FUNCTION TABLE
OUTPUTS
A2
A1
A0
GS
EO
Z
Z
Z
H
H
Z
Z
Z
H
L
L
L
L
L
H
L
L
H
L
H
L
H
L
L
H
L
H
H
L
H
H
L
L
L
H
H
L
H
L
H
H
H
L
L
H
H
H
H
L
H
FAST AND LS TTL DATA
5-1
SN54/74LS348
SN54/74LS848
8-INPUT PRIORITY ENCODERS
WITH 3-STATE OUTPUTS
LOW POWER SCHOTTKY
J SUFFIX
CERAMIC
CASE 620-09
16
1
N SUFFIX
PLASTIC
CASE 648-08
16
1
D SUFFIX
SOIC
16
CASE 751B-03
1
ORDERING INFORMATION
SN54LSXXXJ
Ceramic
SN74LSXXXN
Plastic
SN74LSXXXD
SOIC
H = HIGH Logic Level
L = LOW Logic Level
X = Irrelevant
Z = High Impedance State

SN74LS348DG Summary of contents

  • Page 1

    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 ...

  • Page 2

    SN54/74LS348 SN54/74LS848 (5) EI (10) 0 (11) 1 (12) 2 (13) 3 (1) 4 (2) 5 (3) 6 (4) 7 SN54 / 74LS348 GUARANTEED OPERATING RANGES Symbol Parameter V CC Supply Voltage T A Operating Ambient Temperature Range I OH ...

  • Page 3

    SN54/74LS348 SN54/74LS848 DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE S Symbol Parameter V IH Input HIGH Voltage Input LOW Voltage Input LOW Voltage V IK Input Clamp Diode Voltage Output HIGH Voltage A0, A1, ...

  • Page 4

    SN54/74LS348 SN54/74LS848 AC CHARACTERISTICS ( 5 From From To To (Input) (Output) Symbol PLH 1 thru 7 1 thru A0 ...