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OPA1622 Pop Noise

Shu-Cheng LIN
Guru 11785 points
Other Parts Discussed in Thread: OPA1622, TPS65131, LME49720

Hi Sir, 

Sorry to bother you.

We have use OPA1622, now have pop noise issue.

OPA1622 V+/V- is +15v/-15v. It's use TPS65131 to provide it.

When V+ turn on, we saw short pop noise at Input/output. Please refer as below

1.Dark blue is OPA1622 pin2 V+/15v.

2.Blue is OPA1622 pin8 EN.

3.Green is OPA1622 pin9 output

4.Purple is OPA1622 pin10 Input

We have disconnect input( Float Pin10), Please refer waveform

We have disconnect input(P10 tied 2200pF to GND), Please refer waveform

Is this pulse is normal? 

If Yes, We would like to know where will make this noise. Power or?? and how to fix it.

If No, Does TI have other solution can cover it?

By the way, OPA1622 input side is from two LME49720 provide.

  • 0
    TI__Genius 15410 points
    Hello,

    Can you please share your schematic with us? Please label what has been disconnected in the schematic.

    Leaving pins floating is never recommended, providing the schematic will help trouble shoot the cause of the pop noise at the input/output.

    Also, adding capacitance to the inverting input to ground is not recommend because it causes delays in the feedback which in turn cause stability issues.