ADS1257: INDUSTRIAL TEXAS INSTRUMENTS BASED IEPE SYSTEM SCHEMATI REVIEW

Hi Ignacio,

I looked over your schematic and only have a few comments ...

- The LDO's you're using have plenty of current drive. I don't see any issues with sharing one LDO for multiple ADCs so long as you keep decoupling capacitors close to each ADC.

- (Layout comment) Route REFN back to pin 4 of the REF5025 before connecting to AGND to avoid common-impedance coupling of ground noise into the ADC's reference.

- Make sure capacitors on analog inputs are C0G-type (i.e. low voltage coefficient of capacitance) to avoid signal distortion.

- In the input signal path it looks like you're attenuating the input signal by 2 and then gaining it up by 2 (correct me if I'm wrong). Though not a problem, if you're able to do without this circuitry it may help to reduce noise and other errors that get introduced at each of the signal conditioning stages.

- Finally, pay attention to the reverse leakage currents of the diodes that you've placed in the analog signal path. Especially at higher temperatures, diode leakage currents can be quite significant. These currents will flow through the connected resistor dividers and RC filter and may cause additional offset and offset drift errors. I might suggest looking for a lower-leakage TVS diodes in place of the Schottkey diodes.

Best regards,
Chris