AD7190 and oscillation issues (SR#: 1238093)

Document created by analog-archivist Employee on Feb 23, 2016
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When the overvoltage is negative, the output conversions oscillate from
000000hex to FFFFFF hex. But when
the overvoltage is positive, no oscillations occurs.   

 

Reasons and work-around:

The overvolat is exceeded and is negative, this appears to happen to the sinc4
filter's response.

Although the output conversions oscillate when the negative overvoltage is
present, the ERR flag in the status register still indicates that an
overvoltage is present. So, you could monitor the status register and this will
identify the presence of an overvoltage.

Another option is to use the sinc3 filter rather than the sinc4 filter. When
the sinc3 filter is selected, the oscillations do not occur. So, when a
negative overvoltage is present, the output conversions stay at 000000 hex. You
are using an output data rate of 10 Hz. At this rate, the noise performance of
the AD7190 when using a sinc3 filter is very similar to the noise performance
when using the sinc4 filter. So, choosing the sinc3 filter may be a better
option.

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