Philips PM2517E - Dual 1-0 F4 Decoder;Demultiplixer

l
l
43
l
l
1
3-4-2.
HEF
4555 B Dual
1-0f4
decoder/demultiplixer
HEF 4555
a
'l
to 4 decoder-demultiplexer
is
used
to decode
the digit select
outputs
Ds1 and DS2 from
oo 0059.
In case
of overload
signal ovL
becomes logic
I and forces
the
outputs 4,6
and 7
of the HEF 4555
B to low.
which
means
that the
digits'lOo,
101
and 103 are
blanked.
Vss(-8.5V)
03
02
0l
00
AO
GND
+
vss
(-8
5V
)
I
-ltt
tuu
u-
--.r
5T 2
/.82
rtg.
J t,
03
a2
0l
00
E
GNo
I
v
HEF 1555
Fis.30.
The HEF
4555
B is a dual
1 of4 decoder/demultiplexer.
Each
has
two address inputs
(Ag
and A1),
an
active
LOW
enable input
{ET.
and four mutually
exclusive
outputs which
are active H IGH
(O0
to 03).
When
used
as a decoder,Ewhen-H
lG H, forces
Og
to 03 LOW. When
used
as a demultiplexer.
the appropriate
output is
selected
by the data
on A6
and A1. All
unselected
outputs
are LOW.
I
I
s7
^l
>__!J
PINN
ING
Aq
and 41
Og
to 03
enable inputs
(active
LOW)
address inputs
outputs
(active
H
IGH)
r---l
OUTPUT
Ao At
Og
O1 o.>
o3
0
0
i
I
0
1
0
1
1
0
0
0
0
I
0
0
0
0
,l
,l
0
0
0
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