Analog Output; Connecting Analog Output Loads; Minimizing Glitches On The Output Signal - National Instruments NI USB-6008 User Manual And Specifications

Analog Output

The NI USB-6008/6009 has two independent analog output channels that can generate outputs from 0
to 5 V. All updates of analog output channels are software-timed. GND is the ground-reference signal
for the analog output channels.
Figure 12 shows the circuitry of one analog output channel on the NI USB-6008/6009.
The main block featured in the NI USB-6008/6009 analog output circuitry is the digital-to-analog
converter (DAC), which converts digital codes to analog voltages. There is one DAC for each analog
output line.

Connecting Analog Output Loads

To connect loads to the NI USB-6008/6009, connect the positive lead of the load to the AO terminal,
and connect the ground of the load to a GND terminal, as shown in Figure 13.

Minimizing Glitches on the Output Signal

When you use a DAC to generate a waveform, you may observe glitches in the output signal. These
glitches are normal; when a DAC switches from one voltage to another, it produces glitches due to
released charges. The largest glitches occur when the most significant bit of the DAC code changes. You
can build a lowpass deglitching filter to remove some of these glitches, depending on the frequency and
nature of the output signal. For more information about minimizing glitches. refer to the
KnowledgeBase document, Reducing Glitches on the Analog Output of MIO DAQ Devices. To access
this document, go to
NI USB-6008/6009 User Guide and Specifications
+5 V
REF(+) REF(–)
12-Bit
DAC
GND
Figure 12. Circuitry of One Analog Output Channel
NI USB-6008/6009
Figure 13. Connecting a Load
and enter the Info Code
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50 Ω
AO
Load
GND
.
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16
AO
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