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ADS1271: Converting negative data

Miguel Amezcua Peregrina
Genius 4015 points
Part Number: ADS1271
Other Parts Discussed in Thread: ADS1292, ADS1294

Hi

Im using the ADS1271 for an EMG project. In this moment Im using an adder to move the signal and mount it at 2.5V. The signal comes from an amplifier with an amplitude of ~+/-2.5V. The amplitude can vary for the kind of signal. 

Im using the ADS1271 in a pseudo differential configuration but I was thinking if there is a way to be able to convert the -2.5V without using the adder.

Thanks!

  • 0
    TI__Mastermind 20845 points

    Hi Miguel,

    the ADS1271 does unfortunately not offer a bipolar supply capability such that it could directly measure bipolar signals which extend below GND.
    Therefore you will need to level shift your signal before feeding it to the ADS1271 analog inputs.

    Devices such as the ADS1294 or ADS1292 which are used in EMG applications as well would offer a bipolar supply capability.
    Those ADCs could directly measure a bipolar signal without any level shifting. However when using a +/-2.5V supply and connecting the negative input to GND, then the positive input could only swing from -2.3V to +2.3V due to the limitations of the internal PGA.

    Regards,