• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 48 subscribers
  • Views 816 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

OPA172: Single-Supply, Electret Microphone Pre-Amplifier Reference Design for OPA172

Lawrence He
Genius 3280 points
Part Number: OPA172

Dear,

our client design opa172 as attached, but wavefrom was something wrong.

opa172.pdf

have any suggstion, if any question.

Please advise me.

Thanks,

Best regards,

Lawrence.

reference:

TI Designs – Precision: Verified Design
Single-Supply, Electret Microphone Pre-Amplifier
Reference Design

  • 0
    TI__Guru**** 157416 points

    Lawrence,

    Assuming headphone is a 32 ohm load. there will be more voltage loss across R70 and C73. Xc=1/(6.28*2.2uF*1kHz)= 72 ohms.
    Headphone voltage will be 3Vpp * 32 ohms / ( 32 ohms + 50 ohms + 72i ohms)
    3Vpp * 32 ohms / ( 82 ohms + 72i ohms)
    3Vpp * 32 ohms / sqrt ( 82^2+ 72^2) ohms
    0.88Vpp ; this is close to actual green signal, so problem identified.