Measurement Computing PC104-DAC06 - Manual (Page 10)

is an analog ground and is the ground reference which should be used for all analog
hookups.
Possible analog output ranges are:
Bipolar Ranges ±10V ±5V
and
Unipolar Ranges
0 to 10V 0 to 5V
Each of the DAC06 outputs are individually buffered through an OP-27 operational
amplifier (OP-AMP). The OP-27s are socketted so that if one fails it can be replaced
in the field. The OP-27 for each channel is located adjacent to the calibration
potentiometers for that channel.
At the full rated output swing of ±10V, each channel is capable of sinking or sourcing
±5 mA. That means a load of 2K
Ω
can be connected to each channel.
If load resistance is raised from 2K
Ω
up to 10 Meg
Ω
or more, the output load on the
DAC decreases. Any load resistor greater than 2K
Ω
is acceptable.
As the load resistance decreases, the output load increases. The OP-27 responds by
producing a lower output voltage. If your DAC06 will not produce the output voltage
specified by the code and range combination, check the load with an ohmmeter.
Under normal circumstances you will not damage the OP-27 by connecting the output
to ground. If your connection results in a failure of the OP-27, chances are there was
some potential at the connecting point in addition to a load at ground or between 0
and 2K ohms. Explore the point with a DVM before reconnecting the DAC06 (and
after replacing the OP-27 of course). Connect the negative lead of the DVM to any
LLGND pin of the DAC06.
3.7 CONNECTOR DIAGRAM
The connector is a male, 40-pin header type connector (Figure 3-4).
The connector accepts female 40 pin connectors, such as those on the C40FF-2, a
two- foot cable with connectors or, for compatibility with the CIO-DAC series, a
BP40-37 adapter (Figure 3-5) may be used along with a C37FF-2 cable.
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