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I have acquired some mcp-6002 op-amps in a SOIC package instead of the DIP I normally use. I have solder these to a SOIC to DIP "converter" so to fit on the breadboard. If I connect them as I do with the DIP (as simple buffers for testing) they don't seem to work, I tested 4 of these and all of them behave similarly, the upper part of the wave is non-existent and I get a small part from the bottom of the signal. Now I tried to put a voltage divider with half-the supply (because they are single supply) feeding the inverting input and the wave appears but the upper part of the signal is kind of low-pass filtered. So the question is, have I damaged these during soldering to the convertors or they behave differently?

enter image description here

correction: "applied"

John Am
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  • Have you tried rotating the adapter board? maybe you soldered the ic on the wrong way. – Linkyyy Jan 11 '19 at 12:06
  • @ Linkyyy Yes I tested the connections several times. They should be identical isn't this right? – John Am Jan 11 '19 at 12:07
  • Sounds strange. Yes they should be identical. Can you show the waveforms? input and output. – Linkyyy Jan 11 '19 at 12:12
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    If the part number is the same, then they should work the same, regardless of package (ignoring minor things like tiny differences in inductance and capacitance that shouldn't be a problem in what you are doing.) The pinout is often the same on DIP and SOIC, but not always. [The datasheet for the MCP6002 says DIP and SOIC have the same pinout.](https://ww1.microchip.com/downloads/en/DeviceDoc/21733j.pdf) – JRE Jan 11 '19 at 12:16
  • I have triple checked the package is the equivalent, I use the mcp-6002 and now I got the mcp_6002i-sn. The datasheet says they are the same – John Am Jan 11 '19 at 12:18
  • @JohnAm - Hi, Where did you acquire these SOIC ICs from? Are you 100% confident of the supply chain being legit? – SamGibson Jan 11 '19 at 12:25
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    @ SamGibson ebay, china. Yes perhaps there is also the possibility to be bad IC's. It has never occured to me again, though. – John Am Jan 11 '19 at 12:27
  • @JohnAm - Thanks. Possible reason posted as an answer. :-( – SamGibson Jan 11 '19 at 12:32
  • As it appears to me, the SOIC IC's I got are not single supply, they must be misnamed... – John Am Jan 11 '19 at 12:40
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    @JohnAm - Agreed, that seems a likely conclusion. However if they are not the *marked* part number, then they could be almost anything else :-( Unless you de-encapsulate the die and *hope* to spot something on it (under the microscope) that leads you to a specific part number, then I don't know how you could get confident about what you *really* have :-( Even if you do find a part number on the die, those devices you have could be *rejects* of that part number, and so not meet the datasheet specifications. In short, as far as I can see, all bets are off :-( – SamGibson Jan 11 '19 at 12:46

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Unfortunately this won't be the first time of ICs marked X not behaving as component X should do, having come from Ebay / AliExpress etc.

Since you have some known-good DIP versions of this device, and (excluding gross soldering mistakes) the SOIC version of this device should behave the same, I would be concerned that you don't have genuine, working ICs of the marked part number. We had another example of this situation with EEPROMs sold through AliExpress, in a question a few days ago. Sorry...

SamGibson
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