• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 47 subscribers
  • Views 655 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.

PGA280: Problem with Vocm and digital inputs

Ali Reeza
Expert 1250 points
Part Number: PGA280

Hi

I have powered PGA280 with +/- 13 and connected both Vsop and DVDD to + 5 volt, Vson to ground.

Connecting Vocm to 2.5V and shorting input, 2 volt appears on output. Reading output while increasing Vocm from zero I noticed that there no problem till I pass 1.7 volt. After that the output is not equal to Vocm.

Also looking at all digital inputs when  all connect micro-controller pins to them voltage drop to approximately to 3V. I have isolated micro-controller signals from PGA280 with MAx14131.

Thank you

  • 0
    TI__Genius 13600 points
    Hi Alireza,
    When shorting the inputs, do you simply connect the two, or do you connect both inputs to GND? it's possible that simply shorting the two inputs may still result in an input common mode violation.

    Would it be possible to see your schematic? This may help us answer this question.
  • 0 in reply to Alex Davis
    Expert 1250 points
    Dear Alex

    Thank you for help. I found the the cause. I have used PGA280 output in single ended mode. Not reading datasheet carefully! I tied Von to ground which was the the cause for all of problems.

    Cheers