Specifications
Probably the best
use
of
this
feature
is
to
set
5W10
equal
to
the
number
of
channels
is
use
assuming
that
channels
are
assigned
contiguously
from
channel 0 upwards,
Then
the
MUX
address
register
can
be
used
to
select
what
subset of these channels
are
scanned.
The
most
frequently
scanned
signals should
be
connected to the
higher channel
numbers.
The
most
significant
four
bits
of
the
MUX
address
register
and
of
SW1D
are not used
on
the
ADZ12
but
rather
are
run
to connector
P3D.
By
adding expander boards,
this
provides for expansion for
up
to
256
input channels.
5b.
5ignal Input Options
The
six
pin
jumper
area
"S" (See Jumper Area Numbering -
Daughter Board) allows the multiplexer inputs to
be
configured
as single-ended,
differential,
or
psuedo-differential.
The
latter
is
a
variation
of
the single-ended configuration
where
the
common
return
line
from
the input
signals
is
allowed to
float
with respect
to the module's analog ground.
By
tying the
return
line
to the
low
side
of the
differential
input
amplifier
(pin
12B
on
the
module)
which
is
available
on
all
modules
but the
DT5703,
common
mode
noise
voltages appearing
between
the
return
line
and
analog ground are
rejected.
Any
single-ended
module
can
be
connected
for
psuedo-
differential
operation, but
some
of
the
modules
come
in
only
single-
ended
or only
differential
versions
so
that
all
three
modes
of
operation
may
not
be
possible. A
differential
module
may.
of
course,
always
be
connected as a single-ended
unit
by
grounding
one
of
each
differential
input
pairs.
but
this
wastes
half
of
the inputs
in
the process
and
gives
no
advantage over
differential
operation.
To
connect a
module
for
single-ended operation, jumper lS to
25.
(See
Jumper
Area
Numbering
- Daughter Board)
The
multiplexer
actually
consists
of
two
8 channel units
rather
than
one
16
channel
one. This jumper connects the outputs
of
these
two
multiplexers
together thus
creating
one
16
channel
MUX.
Next, jumper
35
to
4S
thereby connecting the
low
input
of
the
differential
amplifier
to
the input signal
return
line.
The
h,gh input
of
the
differential
amplifier
is
internally
tied
inside
the
module
to
MUX
OUT
HI
which
is
jumper pin 15.
Finally.
jumper
5S
to
65
to connect the signal
return
line
to analog ground. Psuedo-differential operation
;s
achieved
by
leaving the
last
jumper
off.
For
true-differential
operation, jumper
25
to 35. This runs
the multiplexed output
of
the
low
side
of
the
differential
input
pairs
to the
low
input
of
the
differential
amplifier.
Thu~two
eight
channel multiplexers
now
work
together to switch
pairs
of
si~~a1
inputs
into
the high
and
low
inputs
of
the
differential
amp-lifier.
In
general,
this
change also
requires
manipulation
of
the multiplexer address
and
control
lines.
Such
changes
depend
strongly
on
the
module
type
and
may
require
attention
to jumper
area
C.
(See
Jumper
Area
Number
- Daughter Board)
Differential
operation should
also
have
55
jumpered to 65.
11