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Part Number: LM358A
Currently facing some issues with the LM358A oscillation. Can you share with me how to filter out or reduce this oscillation from below schematic. The waveform also provided for your further reference. Please help to advise.
Regards,Ronald MichallickLinear Applications
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In reply to Ron Michallick:
I would like to confirm the below suggestion from you.
"Let's start with delay factor, try adding a 2k resistor from pin 1 to ground."
The above information, 2K resistor adding from op-amp pin 1 to ground is it add a 2K resistor before the 100pF capacitor?
"First try bigger C1, there is no maximum limit other than forward gain bandwidth becoming less."
The C1 you mention here is it a 100pF cap?
Previously tried to adjust the C1 from 30pF to 680pF and tested with the above attached picture I get a better waveform when C1 is 95pF to 100pF.
I also trying around with two resistor above (100ohm & 10Kohm). The oscillation result that I can obtain is the above resistor and capacitor value combination (the previous waveform attached).
Do I still need to increase the C1 value to try on?
In reply to Electrobud:
Thanks for your suggestion the waveform is stable by adding 2K resistor at Op-amp output (Pin 1, before the 100pF cap) to Ground. Currently faced on different voltage changes there will have a small peak at the initial waveform (see the red circle). Time division: 100us
After zooming in to 10us time division as picture below shown, there are a small peak at the initial waveform (see the red circle):
I'm trying to adjust the resistors values but it doesn't helps at all. Will there any method to filter out this small peak? Is this is a typical characteristic of this op-amp and can it be ignored?
This is a small overshoot that is a result of the fast rise of the input signal. The LM358A output can not rise that fast due to slew rate limitation. The overshoot is the recovery out of slew rate limit.
I do not see any issue with this small overshoot, I would ignore it.
Trying to fix it would round the output edges too much and hurt response time.
Attached are the clearly visible in the schematic, but often not comprehended facts about LM358.
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