• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 46 subscribers
  • Views 438 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS1298: A few doubts about power supplies

Rodrigo Beltran
Prodigy 10 points
Part Number: ADS1298

Hi there,

I am working on a project with the ADS1298, and reviewing the datasheet I have some doubts with the power supplies.
First, two types of sources are specified, analog (AVDD) and digital (DVDD) both suggested with different voltages. Then, you have the option of feeding the circuit in a "unipolar" or "bipolar" way, in my case it would be a unipolar way and this is where I have some questions:

1) Is it necessary to use two sources to power the ADS1298?
2) Can I power the ADS1298 with a digital source and make AVDD = DVDD? and therefore AVSS = AGND and supply the circuit with 3.3v?
3) What is the specific difference between the analog and digital source in this case?

To guide a little about what I want to do, it is a cardiac signal monitoring system, using the ADS1298 and a microcontroller (ESP32), initially I would only use 2 channels of the ADS1298 (RA-LA-LL) but in the future, after carrying out some tests, I intend to increase the number of channels and electrodes, that is why it is the choice of the ADS1298.

Your answers would help me a lot to carry out my project and that it works correctly.

Thank you

Rodrigo Beltrán.

  • 0
    TI__Guru 55062 points

    Hi Rodrigo,

    As you said, AVDD powers the analog portion of the device while DVDD powers the digital portion of the device. Having multiple options for how to configure these power supplies allows more flexibility to the designer. 

    Using the same 3.3V voltage source for both AVDD and DVDD will be fine. You will simply need to make sure that the source is capable of providing enough current for both AVDD and DVDD.

    For AVDD, the analog inputs must be within the common-mode range of the PGA, which is roughly mid-supply or 1.65V in your case. Hence why using a bipolar supply on the analog side of the device is sometimes helpful, the input signal can be centered on GND which would be mid-supply. Further information on common-mode input range can be found in the datasheet.

    The power supply for DVDD sets the magnitude that the digital signals are clock ed in/out of the device and should be the same as your ESP32. 

    Please let us know if you have further questions!