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LM358B: sch review

Part Number: LM358B


Tool/software:

Hi Team, 

May I have your support to review below SCH? Thanks! 

  • Kailun,

    The circuit is a family standard op am configuration, and I don't see any issues.  Below is a summary of things I looked at and did not check.

    1. The main thing that I checked is stability.  Placing a 100nF capacitor directly on the output of an op amp will generally cause it to oscillate (become unstable).  One solution to this issue is to place an isolation resistance between the op amp output and capacitive load (R3007).  Of course, it is important to choose a large enough isolation resistance to make the circuit stable.  Your selection of 1k works well.  Thus, no issues with stability.
    2. Another thing I looked at is the selection of the feedback capacitor.  100nF seems large compared to what I would  usually expect.  This capacitor limits the bandwidth of the circuit to f = 1/(2*pi*RF*CF) = 1/(2*pi*51k*100nF) = 31Hz.  If you want a 31Hz bandwidth than this capacitor is ok, but that seems like a low bandwidth.  
    3. The 1k resistor (R3005) on the non-inverting input only acts as a protection device.  I think it is good to add protection resistors, so I think this is a good choice.  I only mention this because you may have other goals for this resistor.  if it was added as a protection device, than I agree with the choice.

    I hope this helps.  Art

  • Thanks Art! It helps a lot!