Tried all over internet...but not found what it is. Any help appreciated. What is that one (55A5)

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    \$\begingroup\$ Judging by the way those 4 pads are all connected together it's probably a MOSFET of some sort. \$\endgroup\$
    – brhans
    Nov 22, 2017 at 13:46
  • \$\begingroup\$ Similar questions are asked almost daily so that's why we have a search function leading you to this question and answer: electronics.stackexchange.com/questions/334128/… Follow that procedure and if that does not provide an answer there is little hope that the component can be identified. \$\endgroup\$ Nov 22, 2017 at 13:48
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    \$\begingroup\$ As brhans noticed, the way pads are connected are would indicate this is a single MOSFET (or eventually BJT) in SC74 / SOT-23-6 / SOT-26-6 or variants of the like. There isn't that many of them, because usually such 6-pin packages are used for dual mosfets, but this clearly isn't the case here. So, here is a search on mouser with thoses criterias, your component could be there. Check each datasheet. Or just take one randomly and solder it. If you're lucky, it could work. \$\endgroup\$
    – dim
    Nov 22, 2017 at 14:20
  • \$\begingroup\$ @KKostas for future reference: electronics.stackexchange.com/questions/334128/… \$\endgroup\$
    – Voltage Spike
    Apr 6, 2018 at 20:12

1 Answer 1


It might be FDC655AN MOSFET (obsolete) - replaced by FDC655BN (datasheet: http://www.onsemi.com/pub/Collateral/FDC655BN-D.PDF).

  • \$\begingroup\$ desqa , thank you for your answer , was very helpful. I found an other one but not sure if its the one . Seems like FDC655AN - FDC655BN you mentioned. "SST3215'' (datasheet: secosgmbh.com/datasheet/products/MOSFET/SOT-26/SST3215.pdf ). \$\endgroup\$
    – KKostas
    Nov 24, 2017 at 7:06
  • \$\begingroup\$ Yes, pinout is the same, but the marking is different - in this case it is "3215" (as mentioned on the first page). The parameters are also quite different, but it depends on your application if it matters. Good luck with the search! \$\endgroup\$
    – desqa
    Nov 24, 2017 at 7:13
  • \$\begingroup\$ I also found that the marking "55A" is used by MIC2033-55AYM6 power switch (datasheet: ww1.microchip.com/downloads/en/DeviceDoc/MIC2033-B.pdf). But, unfortunately, the pinout doesn't quite match up. \$\endgroup\$
    – desqa
    Nov 24, 2017 at 7:18

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