ADS1258: ADS 1258

Part Number: ADS1258

Hi,

I am unable to get the accurate readings for the ADS 1258 interfaced to ST mic(Please visit the site to view this file)ro controller in our design. I had referred to other posts in the forum regarding the design and identical problems.

Following are the deviations observed in our design with reference to other posts:

1. Add 47 ohms termination resistors for ADC serial interface.
2. Add a low pass RC filter of 150 Hz at output stage of OpAmp or external signal conditioning circuit of ADC.
3. Add a buffer to reference voltage generator and a differential filter capacitor between VREFP and VREFN to help stabilize and reduce the voltage reference noise.
4. Following is the ADC layout.

Deviations observed in analog and digital grounds and placement of the Rg and Rf in the op amp stage are highlighted in the above picture.

Please do suggest me any changes required apart from the above mentioned points to correct the problem with accuracy.

Schematics and readings observed are provided in the attachment.(Please visit the site to view this file)