• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 46 subscribers
  • Views 528 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: ADS1298 PCB, ground design

Mary
Prodigy 120 points
Part Number: ADS1298


Hello

I have some questions in designing ground of my PCB.(4 layer)

1-Is it better to break my ground plane into digital ground and analog ground (and connect them in one point), Or  to have one solid plane and keep digital and analog components away from each other?

2-I want to use a switching 6v adapter for supply the board. How should I connect adapter ground to PCB ground? (directly? with inductor? or ..)

3-Is it necessary to filter adapter voltage, on PCB? If yes, please recommend me some good ans simple options.

thanks in advance,

  • 0
    TI__Guru 66906 points

    Hello Mary,

    Thank you for your post.

    1. My preference is always to use a solid ground plane, unless it's absolutely necessary to separate them. A careful placement of analog and digital components with adequate decoupling capacitors can make a big impact. Ideally, the return currents from the analog side of the board will flow back through the digital side, not the reverse. Therefore, switching power supplies and digital signals should be grouped on the same side, if possible.
    2. Again - if placement is well thought out, a solid ground connection should be fine. An inductor can help mitigate some issues, but it can also create issues if an active component cannot receive the dynamic current that it requires to function properly (i.e. you may "starve" the component when it demands a sudden increase in power). 
    3. I assume the 6-V adapter will be used to regulate other supply voltages on the PCB? Generally, switching supplies are used to efficiently regulate the incoming voltage close to supply voltage that is required. Then, an LDO with high PSRR is used to regulate the exactly supply voltage required. An LDO can help to reduce the switching ripple from the incoming supply source. Adequate decoupling and noise-reduction capacitors will help to reduce supply noise.

    Check out this online training on delta-sigma ADC performance tips:

    https://training.ti.com/delta-sigma-adcs-power-supplies

    Best regards,

  • 0 in reply to Ryan Andrews
    Prodigy 120 points

    Hello Ryan

    I'm sorry for replying too late.

    Thanks you. Your answers are really useful, not just for my current project.

    Yes I'm using a 6v adapter and then regulate it with LDO regulators to 5v and 3.3v.