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ADS1261: 60Hz noise in the measurements

Part Number: ADS1261


Hello,

We are working on a design that uses the ADS1261 to measure the outputs of four load cells. During testing, we are encountering a noticeable 60Hz noise in our data.

Using the EVM with the ADS1261 set to 1200 SPS, PGA = 128, and SINC 2 filter, we observe 589 bits pk-pk. However, when we take similar measurements with our design with the ADS1261 set to 400 SPS, PGA = 128, and SINC 2 filter, we observe between 2500-3500 bits pk-pk.

This additional noise has a frequency of 60Hz. For testing purposes, our design uses a USB-FTDI adapter to talk to the onboard microcontroller, although the final design would only typically use the USB port as an alternative power source to batteries.

When we run tests with a laptop that is not connected to wall power, the 60Hz noise disappears. This would seem to confirm that the noise is being conducted over the USB cable. However, as previously noted, this noise is not observed when taking similar measurements using the ADS1261-EVM. Our design actually uses the same LDO to provide power to the ADS1261. Would anyone be able to provide some insights on how better 60Hz rejection was achieved on the EVM?

Regards,

Vincent Politzer

  • Hi Vincent,

    Thanks for your query on E2E forum.

    Have you checked the result at same data rate? I believe it's same as you have, however I want to confirm. I would like to check your schematic including ADC and power supplies to see if you have proper decoupling. Also, your pcb layout will be helpful, thanks.

    Regards,

    Dale