Ametek Thermox CEM O2/TM, User Manual

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C-2 | Thermox CEM O2/TM
To determine the minimum external voltage supply required to power the
current outputs, use the following formula:
VEXTmin = .02 amps (RLoad + Rwires) + 4 volts
where:
VEXTmin = the minimum external voltage required to power
current output circuit
RLoad = the load resistance of the current output device
Rwires = the resistance of the wires
Modulation of External Power loop Using Current Outputs
Figure C-1 shows an example of the connection method when you want to
produce a modulated current loop from an external power supply and a load
device. All current output channels (IOUT1 and IOUT2) can be connected
in the same manner as shown in this figure.
IOUT1 and IOUT2 must share the same power supply if both of these chan-
nels are used, or two power supplies can be “ORed” together using a diode
from each power supply positive terminal (diode anode to power supply) to
the VEXT1,2+ terminal. The power supply minuses would be tied together
and connected to one side of the both loads. The other side of one of the
loads would be connected to IOUT1+ terminal, and the other side of the
other load would be connected to the IOUT2+ terminal.
For each current output channel used in a current loop modulation applica-
tion, the jumpers should be removed for that channel.