ADS1299: Connecting Mid-supply directly to the body instead of Biasout

Mojtaba pourdara

Part Number: ADS1299

I saw a EEG system using ADS1299 that used Mid-supply directly connected to the body instead of connect Biasout. Is this correct and can we design the same way? If so, for Vsuuply=5 should we use 2.5 Volts and 0 Volt for 2.5 Supply?

Thanks

over 5 years ago

0 Alexander Smith over 5 years ago

TI__Guru 55342 points

Hi Mojtaba,

Am implementation like this is fine.

For power supplies, the device can be run in a unipolar configuration where AVDD = 5V and AVSS = 0V, or in a bipolar configuration where AVDD = 2.5V and AVSS = -2.5V. For additional information, please consult the datasheet.

0 Mojtaba pourdara over 5 years ago in reply to Alexander Smith

Prodigy 230 points

Hi Alexander

Thanks for your answer

I mean for Vsupply=5 V, can we connect midsupply=2.5 V to the body instead of BIASOUT?

0 Alexander Smith over 5 years ago in reply to Mojtaba pourdara

TI__Guru 55342 points

Hi Mojtaba,

You can connect mid-supply, 2.5V, to the body. This will ensure that the measurement is within the common-mode range of the PGA, however you would not get the added benefit of canceling out additional common-mode noise by using the BIASOUT feature. You would have to rely on the common-mode rejection ratio of the PGA amplifiers and digital filtering.

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ADS1299: Connecting Mid-supply directly to the body instead of Biasout