ADS1299EEGFE-PDK: Differential Inputs

joao costa

Part Number: ADS1299EEGFE-PDK

Hi Ti

I'm having trouble measuring signals with the ADS1299.
These are my settings, can you help me?

I used the following procedure:

"

Differential Inputs
To digitize eight differential inputs,
1. Set all jumpers to factory defaults as described in Section 2.5.
2. Remove jumpers from pin 5-36 of J6.
3. Provide the differential inputs on the even pins 6-36 of J6."

*signal generated on CH1

Thank you!

João Victor

over 5 years ago

0 Alexander Smith over 5 years ago

TI__Guru 51211 points

Hello Joao,

Thanks for your post!

As the paragraph states after these steps, "While used with differential inputs, care needs to be taken to ensure that the analog inputs are within the input common mode range of the PGA. If the input differential signal is centered around 0V, the ADS1299 needs to be operated with a bipolar supply. Refer to Section 4.1 for details on setting the EVM to operate with a bipolar supply."

What is your power configuration and what is the input signal being applied?

0 joao costa over 5 years ago in reply to Alexander Smith

Prodigy 95 points

power configuration: 6V unipolar

input signal being applied: f = 20Hz; Vpp = 30mV; Voffset = 50mV

Using the configuration "Single-Ended Inputs", as in the link "e2e.ti.com/.../741999", I got the correct results, but with "Differential Inputs" not published as expected.

Thank you for the quick return!

João Victor

0 Alexander Smith over 5 years ago in reply to joao costa

TI__Guru 51211 points

Hi Joao,

Is the input signal being applied truly differential or single-ended?
I assume that the signal is single-ended and being applied to the positive terminal.
What is on the negative terminal?

Take a look at section 9.3.1.3.1 Input Common-Mode Range of the ADS1299 datasheet, and this video may help as well: training.ti.com/ti-precision-labs-adcs-sar-adc-input-types

0 joao costa over 5 years ago in reply to Alexander Smith

Prodigy 95 points

Hialexander

Now it's clear, sorry for the mistake, I'm still starting my electrical studies.
I was applying a single-ended signal.

Thanks a lot for the help!

Best regards,

João

0 Alexander Smith over 5 years ago in reply to joao costa

TI__Guru 51211 points

Hi Joao,

No worries! I'm glad that it's clear now. Were you able to correctly measure a differential signal?

Please let us know if you need more help or have additional questions.

0 joao costa over 5 years ago in reply to Alexander Smith

Prodigy 95 points

Hi alexander ,

Yes, I got it.

thanks for the help!

João Victor

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ADS1299EEGFE-PDK: Differential Inputs