I am looking at an EEG acquisition board, specifically where the electrode leads enter the board just prior to RC filtering (channel RC components in the image) and input into an ADS1299 front-end (two 6-pin SMDs at right).

enter image description here

I see an SMD component (green), perhaps a switch or a buffer, which appears to be connecting the inverting input of one (of the eight) amplifiers with the non-inverting input of the next channel up.

What might this SMD component be? I've tried unsuccessfully looking in SMD databases.

enter image description here

  • 2
    \$\begingroup\$ Please review our guidelines on component ID questions. \$\endgroup\$
    – Null
    Nov 7, 2022 at 15:59
  • \$\begingroup\$ Did a search but nothing obvious turned up. Best guess comparator or opamp. See if you can trace out which pin is Vcc, GND and so in. \$\endgroup\$
    – winny
    Nov 7, 2022 at 16:37

1 Answer 1


From the part location we can surmise that it's related to input protection, probably a TVS array, and from the application we know it must be a low-leakage part.

It's a TI TPD4E1B06DCKR 4-Channel Ultra Low Leakage ESD Protection Device

Photo is from LCSC:

enter image description here

  • \$\begingroup\$ Its amazing that they take an actual picture of the device instead of using a generic SOT23-6 picture/render. I can't understand how that would make sense. \$\endgroup\$
    – Wesley Lee
    Nov 7, 2022 at 18:21
  • \$\begingroup\$ @WesleyLee It's a tremendous service and doubtless very labor intensive. Imagine if they OCRd all that information into an SMD finder with the actual photos for reference. \$\endgroup\$ Nov 7, 2022 at 23:08

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