ADS131A04EVM: Random spikes in data

Stephen,


What is the configuration of the device when this data was taken? If you can, send a screen shot of the configuration registers. If there is some periodicity in the spikes, can you show a plot of that as well?


Joseph Wu

The channel 1 inputs are shorted and connected to ground.  Repeated test with analog supply set to +-2.5V, which puts the analog inputs at mid-scale of supply.  Again received spurious spikes, sometime a single spike, some times a few spikes with a regular period.

Stephen,


This may take me a little time. I need to talk to a few people about this and see if they have any insights. I'll also try making some measurements with my EVM.

Give me a day to check it out.


Joseph Wu

Thank you, Joseph. I've found that when taking data records of a few thousand points that the problem occurs at least once per 10 acquisitions.

Stephen,


I did manage to catch the characterization engineer on this device and he thinks this looks like EMI rather than tonal behavior. When he's seen tones on this device, it looks like extra noise in the measurement rather than periodic spikes in the time domain. That was his opinion on both photos shown in the previous posts.

His recommendation would be to try putting some enclosed grounded shielding around the EVM. To his recollection, there had been problems with EVM measurements and nearby cell phone interference. Any EMI could set off the measurement.

Again, I'll try to make some measurements on my own to see what I see.


Joseph Wu