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11-2
HEF4751V
LSI
UNIVERSAL
DIVIDER
The
HEF4751
V
is
a universal
divider (U.D.)
intended
for
use
in
high
performance phase
lock
loop
frequency
synthesizer systems.
It
consists of
a
chain
of
counters operating
in
a
programmable
feedback
mode.
Programmable
feedback
signals are
generated
for
up
to three external
(fast)
^10/11
prescaler.
The
system comprising one
HEF4751
V
U.D.
together
with
prescalers
is
a fully
programmable
divider
with
a
maximum
configuration
of:
5
decimal
stages, a
programmable
mode
M
stage
(1
<
M
<
16,
non-
decimal
fraction
channel
selection),
and
a
mode H
stage
(H
=
1
or
2,
stage for half
channel
offset).
Programming
is
performed
in
BCD
code
in
a
bit-parallel, digit-serial
format.
To
accommodate
fixed or variable
frequency
offset,
two numbers
are
applied
in
parallel,
one
being
subtracted
from
the other
to
produce
the
internal
programme.
The
decade
selection
address
is
generated
by
an
internal
programme
counter
which
may
run continuous-
ly
or on demand.
Two
or
more
universal dividers
can be
cascaded, each extra
U.D.
(in
slave
mode)
adds
two
decades
to
the system.
The
combination
retains
the
full
programmability
and
features
of
a
single
U.D.
The
U.D.
provides
a
fast
output
signal
FF
at
output
OFF,
which
can have
a
phase
jitter
of
±
1
system
input
period, to
allow
fast
frequency
locking.
The
slow output
signal
FS
at
output
OFS, which
is
jitter-free,
is
used
for
fine
phase
control
at a
lower
speed.
28][^[2^[25][2^[23][2^[ri][2^(T9]n8]fT7][^
DD
OFF
Rl
OFS
.
OFBq
OFBo
'
OFB
OSY
IN
83
83
B
Bf
SI
HEF4751V
A3
A2
Ai
Aq OD0 ODg OD4 OD3 OD2
OD-|
ODq
PE
PC
^55
[9]'
[j^ [1^ 11^ Q3J
LliJ
7Z84464
Fig.
1
Pinning diagram.
SUPPLY
VOLTAGE
rating
recommended
operating
-
0,5
to
-1-18
4,5 to 12,5
V
HEF4751VP
:
28-lead
DIL;
plastic
(SOT-117).
HEF4751VD:
28-lead
DIL;
ceramic
(cerdip)
(SOT-135A).
HEF4751
VT
:
28-lead mini-pack;
plastic
(SO-28;SOT-136A).
FAMILY DATA
IqD
Limits
category LSI
see
Family
Specifications
May
1983
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