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PGA308: PGA308 Output Voltage increase at Power up /Power down

Akihisa Tamazaki
Genius 11465 points
Part Number: PGA308

Hello team,

My customer would like to know the PGA308 output voltage behavior at Power-up and Power Down.
He had some questions as below about PGA308. Would you please advise after checking attached excel file.

Q1) Overshoot at output pin of PGA308 like the attached excel file was observed at PGA308 powered up. It seems that PGA308 causes the overshoot. Is it correct?
Q2) At the power down, we can see the overshoot. It seems that PGA308 causes the overshoot. Is it correct?
Q3) Can we reduce the overshoot using configuration of PGA308?

PGA308 Captured waveform,  Schmatics and consititon as below.
/cfs-file/__key/communityserver-discussions-components-files/14/4150.PGA308PowerON_0FFF_OFF-waveform_5F00_180319.xlsx

Please tell me so if this penomenon is caused by PGA308.

Your advise would be so appreciated.

Best Regards,
Akihisa Tamazaki

  • 0
    TI__Expert 6250 points
    Hello Akihisa-san,
    Power-up and power-down output transients are not uncommon on amplifiers, as internal circuitry may run out of voltage headroom to properly maintain a fixed output voltage. I suspect that these transients your customer is seeing are caused by the PGA308. It may be possible to reduce the magnitude of this transient by aggressively low-pass filtering the output of the PGA, but that would degrade the bandwidth significantly.
  • 0 in reply to Alexander Davis
    TI__Genius 11465 points
    Alex-san,

    Thank you for your comment. I understand it.
    If the customer ask additional question, I may post another E2E thread.

    Best Regards,
    Akihisa Tamazaki