MC54F148 View Datasheet(PDF) - Motorola => Freescale
Part Name
Description
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MC54F148 Datasheet PDF : 3 Pages
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MC54/74F148
GUARANTEED OPERATING RANGES
Symbol
Parameter
VCC
TA
Supply Voltage
Operating Ambient Temperature Range
IOH
Output Current — High
IOL
Output Current — Low
Min
Typ
Max
Unit
54, 74
4.5
5.0
5.5
V
54
–55
25
125
°C
74
0
25
70
54, 74
–1.0
mA
54, 74
20
mA
FUNCTIONAL DESCRIPTION
The F148 8-input priority encoder accepts data from eight
active LOW inputs (I0–I7) 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
erroneous information at the outputs. A Group Signal output
(GS) and Enable Output (EO) are provided along with the
three priority data outputs (A2, A1, A0). 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.
FUNCTION TABLE
Inputs
Outputs
E1 I0 I1 I2 I3 I4 I5 I6 I7 GS A0 A1 A2 EO
HXXXXXXXXHHHHH
L HHHHHHHHHHHH L
LXXXXXXXL L L L LH
LXXXXXXLHLHL LH
L XXXXX LHHL LHLH
L XXXX LHHHLHHLH
L XXX LHHHHL L LHH
L XX LHHHHHLHLHH
L X LHHHHHHL LHHH
L LHHHHHHHLHHHH
H = HIGH Voltage Level; L = LOW Voltage Level; X = Don’t Care
LSB
MSB
ENABLE
0 1 2 3 4 5 6 7 E1
’F148
A0 A1 A2 GS
0 1 2 3 4 5 6 7 E1
’F148
EO A0 A1 A2 GS
A0
A1
A2
A3
FLAG
Figure 1. Application: 16-Input Priority Encoder
FAST AND LS TTL DATA
4-60
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