ADS1299: Connecting BIAS and Reference electrodes with multiple ADS1299

USER1234NEURO

Part Number: ADS1299

Hi,

Currently we are developing an 32 channel EEG acquisition system using 4 ADS1299.

We have an issue on how the BIAS and REF electrode need to be connected. We will not be using the ADS1299 daisy- chain feature, but we will be using a common SPI line between the ADS1299 and 4 seperate CS lines.

Below i have two options for the BIAS and REF setup. We have researched various sources and it seems there are multiple ways how the BIAS electrode is connected when using multiple ADS1299.

Can anyone suggest if the setups below are correct and if so which is the best setup to use?

Thanks!

SETUP 1

SETUP 2

over 8 years ago

0 Praveen Aroul over 8 years ago

TI__Mastermind 49906 points

Hello,

I am moving your post to the Precision Data converters forum where the device ADS1299 is supported.

0 Brian Pisani over 8 years ago

TI__Mastermind 38745 points

Hello USER1234EURO,

The bottom diagram is correct. If you look at Figure 37 in the ADS1299 datasheet, you can see that the BIASINV pin has the "average" of all the PGA outputs on it. You can "average" PGA outputs from different devices by simply wiring over the BIASINV pin from another device. However, you still only want to use one amp to drive the signal.

Regards,
Brian

0 USER1234NEURO over 8 years ago in reply to Brian Pisani

Prodigy 45 points

Hi Brian,
Thanks for your reply! Would it be possible if i contact you via email please?

Thanks

0 Brian Pisani over 8 years ago in reply to USER1234NEURO

TI__Mastermind 38745 points

Hello USER1234NEURO,

If there is confidential information you wish to discuss (i.e. schematics, layout, other proprietary design details), then I would be happy to correspond via email. If that is the case, I can reach out to you via the email address associated with your MyTI account, if that is alright with you.

If the topic of discussion is more about the general operation of the device or generic debugging, then I ask that our conversation remain on the forum for the benefit of other folks who might have similar inquiries.

Regards,
Brian