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I have been trying to find what IC this is for ages.

enter image description here

Here is some information on the IC:

  • Found in a wireless gaming mouse (mostly Logitech).
  • It's connected to the mouse buttons/LED (not 100% sure)
  • It's always accompanied by 3 resistors
  • IC marking is 1F5/1F7 (see picture)

I found a similar one in another mouse:

enter image description here

This one looks like it is connected to a 74LVC595, but these ones have a capacitor.

At first I thought it was a Schmitt trigger for the buttons, but I couldn't find any single-channel Schmitt trigger IC with 6 pins.

Any help would be appreciated.

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  • \$\begingroup\$ Is that a LED mounted on top of an IC? Curious, that one's new to me. Could it be the IR diode integrated with some sort of SoC? \$\endgroup\$
    – Lundin
    Commented Apr 6, 2023 at 8:36
  • \$\begingroup\$ There is a RGB LED and that did make me think it might be a driver but tracing the path led me to a button \$\endgroup\$
    – Sharu
    Commented Apr 6, 2023 at 12:39
  • \$\begingroup\$ @Lundin I think that is a surface mount daughterboard. \$\endgroup\$ Commented Apr 7, 2023 at 14:27

2 Answers 2

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They are labelled Q13, Q21 etc, so I'm guessing a transistor, perhaps a pair such as BC847BV, which, at least from Onsemi and NXP, is marked 1F and appears to be in the right sort of package. The 7 is perhaps a date or factory code, which would explain why some are 5.

From your photo, a little tracing (edit: redrawn with 595 correct way around, pin 1 marker appears top right):

enter image description here

Which suggests the following fragment, which looks like a clock input arrangement of the 595. The caps look like bypass.

enter image description here

Datasheets

A numebr of manufacturers have twin-transistors in appropriate packages marked 1F, with this pinout:

enter image description here

Note rotational symmetry. I suggest you measure one accurately to confirm the package, and trace a few of the signals to see if the pinout makes any sense. It's plausible they might want 18 transistors, but I'm not sure what other part they'd want so many of.

I found it on The ultimate SMD marking codes database, looking for 1F in the right kind of package.

The Onsemi BC847BDW1 datasheet:

enter image description here

The NXP BC847BV datasheet:

enter image description here

The Nexperia BC847BS datasheet:

enter image description here

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  • \$\begingroup\$ LCSC has pictures and there is no date code (also missing the dots): lcsc.com/product-detail/…. I don't think this is the right part. \$\endgroup\$
    – nanash1
    Commented Apr 6, 2023 at 8:25
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    \$\begingroup\$ It seems the marking matches Onsemi marking for the same part, answer updated. \$\endgroup\$
    – jonathanjo
    Commented Apr 6, 2023 at 8:48
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    \$\begingroup\$ OnSemi one seems most likely (just by the arrangement of characters). Could also be the Nexperia variant, BC847BS - that one is marked also 1F% (where % is a single character for manufacturing location). All basically the same thing. Diodes Inc have an 847 marked K1F. All would be suitable replacements. \$\endgroup\$ Commented Apr 6, 2023 at 14:53
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    \$\begingroup\$ Looks like it. @jonathanjo I don't have the board with me so i cannot verify that but i think you are right with the schematic. Thank you everyone for helping. \$\endgroup\$
    – Sharu
    Commented Apr 6, 2023 at 15:08
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    \$\begingroup\$ You have mislabeled the last datasheet, it should be Nexperia, not Onsemi. Also, I think the NXP one is most likely superflous - I believe they didn't keep making transistors after divesting and selling Nexperia. \$\endgroup\$
    – jaskij
    Commented Apr 6, 2023 at 17:56
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General rule of thumb, if you see a small, unknown component with a number of pins divisible by 3, the first reasonable guess is an IC housing a number of transistors. Using oszilloscope probes to check for diode-like behavior on a number of adjacent 2-pin combinations can be helpful. But looking at photo, those are either two-transistor ICs, RLC filters for improving the signal characteristics, or thingamajigs responsible for switching the duty cycle of the mouse's LED illumination.

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