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IC Identification Help (SMD Marking 651+, or maybe G51+), SOT-23-6

Discussion in 'Electronic Repair' started by [email protected], Sep 29, 2013.

  1. Guest


    I've got a bad part that I'm trying to find a replacement for... but I can't seem to find out what the original part is. It looks to be a SOT-23-6, with a marking of 651+, or maybe G51+ (I don't see any brand marking on it).It's definitely bad... smoke was coming from the part, and it's very toasty.

    Looking at the circuit, my best guess is that it's some sort of transistor.... with pins 1, 2, and 5 connected together to a copper pour, going to one pin of a transformer. Pins 4 and 6 are also connected together to a wide trace (maybe the power input?). Then pin 3 is connected to a thin trace, going elsewhere on the board (maybe control signal of some sort?). None of the pins are connected to GND.

    Here are a couple pics... one of the chip (with marking visible), and one of the pads with the chip removed.

    Any ideas what this part is? I tried searching various SMD marking sites, but couldn't find any match.

  2. N_Cook

    N_Cook Guest

    Try a datasheet site with a "included within" string search option ?
  3. Guest

    Try a datasheet site with a "included within" string search option ?

    Yeah, I've searched datasheet sites... but I don't think the part number actually includes 651 or G51. Typically small surface mount components put some marking on them, which doesn't actually correspond to its part number. There are quite a few sites that have SMD marking tables, but I haven't found a match. I was hoping maybe someone knew of better SMD marking sites than I do, or recognized a part in that package that would be connected likethis.

  4. JW

    JW Guest

    Could it be a PZT651 Mot SOT223 npn 60V 1A?
  5. Guest

    Aha! I think I found it. It looks to be an NDC651N MOSFET. That was difficult to find because they have so many different package names that are the same thing. I was searching mostly for SOT-23-6, or SOT-26, but they call it a SSOT-6 (and others call it a Micro6, TSOP-6, etc).

    Unfortunately, it looks like the part is obsolete, though I can still get it from China or Hong Kong... if I want to wait a month for it (like: <--note the marking in the pic :)). Or, there's a guy in the US on ebay that's selling ~50 of them for ~$30.

    Or I can find a cross reference. It looks like a couple good cross references that Digikey stocks are the IRLMS1503TRPBF or SI3454ADV-T1-E3 (the Vishay part has slightly lower Rds). Unfortunately they have a slightly different pinout (pin 6 is connected to the source on the original part, but connected to the drain on these cross referenced parts). But I should be able to simply cut that pin, since the rest of the pins are correct, and that's a redundant pin on both chips.

  6. N_Cook

    N_Cook Guest

    I get the impression,generally for SMD codings, that if the code is 2 or
    3 characters, including punctuation or graphics or inverted or other
    alphabet characters then a SMD code. If 3 or more only regular letters
    and numbers then a curtailed part of a long part number, generally
    excluding maker part and package part
  7. Guest

    Quick update... the parts arrived from Digikey today, and I replaced the NDC651N with the SI3454ADV-T1-E3 (pin 6 bent up and over to pin 5), and it worked great.

  8. Guest

    Hi dear pat
    is it for FSH3 spectrum analyzer? I have a problem with it.
    if you have any information about it, please tell me.
    thank you very much keivan
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