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3.
SDM-CD16
Control Pofi Expansion Module with Drivers
POWER CONSIDERATIONS
The SDM-CD16 power requirements
are
large
compared
to most
CSI
products.
For most
applications an external power supply, as shown
in Figure
2,
is recommended
to
power the
SDM-
cD16.
For some
applications it may be convenient
to
use
the
datalogger supply
to
power the
SDM-
CD16. For long term applications the lead acid
power supply available
with
CSI
dataloggers
should be used, allowing the batteries
to
be
float
charged.
lt is not recommended that the
datalogger alkaline
supply be used to power the
SDM-CD16
for long term applications.
lf
the
datalogger lead acid supply
is
used,
the
number of SDM-CD16's
which can be powered
is
limited by the 300 mA current
sourcing capability
of
the wall
charger.
With
a
continuous 6
mA
current
drain per SDM-CD16 and
11
mA per
active
LED, a
maximum of 26 LEDs may
be
powered by the datalogger, after which,
current
is
drawn than
can
be
sourced by the
charger.
lf
this
condition is maintained,
it
will
ultimately lead
to
battery deep discharge,
requiring new bafteries.
lf
the
21X
power
supply is used
to
power
the
SDM-CD16, all low
levelanalog
(thermocouples, pyranometers, thermopiles,
etc.) must be made
differentially. This
is a
of slight
ground potentials created along the
analog terminal strip when
the
12V
supply
is
to
power
peripherals. This limitation reduces
number
of
available
analog input channels
may mandate an e).ternal supply for
the
SDM
cD16.
DATALO66ER
DC
POVER
SUPPLY
FIGURE
2.
Application Block Diagram
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