MC74F148 Motorola, MC74F148 Datasheet - Page 2

• Manufacturer Part Number: MC74F148
• Description: 8-Line to 3-line Priority Encoder
• Manufacturer: Motorola

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H = HIGH Voltage Level; L = LOW Voltage Level; X = Don’t Care
GUARANTEED OPERATING RANGES
active LOW inputs (I 0 –I 7 ) and provides a binary representa-
tion on the three active LOW outputs. A priority is assigned to
each input so that when two or more inputs are simultaneously
active, the input with the highest priority is represented on the
output, with input line 7 having the highest priority. A HIGH on
the Enable Input (E1) will force all outputs to the inactive
(HIGH) state and allow new data to settle without producing
FUNCTION TABLE
V CC
T A
I OH
I OL
E1
Symbol
The F148 8-input priority encoder accepts data from eight
H
L
L
L
L
L
L
L
L
L
I 0
X
H
X
X
X
X
X
X
X
L
Supply Voltage
Operating Ambient Temperature Range
Output Current — High
Output Current — Low
I 1
X
H
X
X
X
X
X
X
H
L
I 2
X
H
X
X
X
X
X
H
H
L
Inputs
I 3
H
H
H
H
X
X
X
X
X
L
LSB
0 1 2 3 4 5 6 7 E1
I 4
X
H
X
X
X
H
H
H
H
L
Parameter
A 0
A 0
Figure 1. Application: 16-Input Priority Encoder
I 5
X
H
X
X
H
H
H
H
H
L
’F148
A 1
I 6
X
H
X
H
H
H
H
H
H
L
A 1
A 2
FUNCTIONAL DESCRIPTION
FAST AND LS TTL DATA
I 7
X
H
H
H
H
H
H
H
H
L
GS
MC54/74F148
A 2
GS
H
H
L
L
L
L
L
L
L
L
A 3
4-60
A 0
H
H
H
H
H
H
EO
L
L
L
L
0 1 2 3 4 5 6 7 E1
Outputs
erroneous information at the outputs. A Group Signal output
(GS) and Enable Output (EO) are provided along with the
three priority data outputs (A 2 , A 1 , A 0 ). GS is active LOW when
any input is LOW; this indicates when any input is active. EO
is active LOW when all inputs are HIGH. Using the Enable
Output along with the Enable Input allows cascading for prior-
ity encoding on any number of input signals. Both EO and GS
are in the inactive HIGH state when the Enable Input is HIGH.
A 1
H
H
H
H
H
H
L
L
L
L
A 0
54, 74
54, 74
54, 74
54
74
’F148
’F148
A 2
A 1
H
H
H
H
H
H
L
L
L
L
A 2
EO
H
H
H
H
H
H
H
H
H
L
MSB
Min
–55
4.5
FLAG
0
GS
ENABLE
Typ
5.0
25
25
Max
–1.0
125
5.5
70
20
Unit
mA
mA
V
C