I have an SMD transistor. As I tested it, I know it's a MOSFET, but the top code is ARRL 1S. All 1S are NPN transistors and I know it's surely a MOSFET. Please help find the correct part number.

photo of unknown device


1 Answer 1


It is an Alpha and Omega AO3422 55V 2.1A n-channel MOSFET.

Image of top code from AO3422 MOSFET

(From AO3422 markings document)

  • \$\begingroup\$ Hi. Thanks for your answer. But how you know that ? \$\endgroup\$
    – mohammad
    Commented Apr 11, 2021 at 17:20
  • \$\begingroup\$ Because the code is " 1S" and i dont see any 1s on ao3422 !!!! \$\endgroup\$
    – mohammad
    Commented Apr 11, 2021 at 17:21
  • 2
    \$\begingroup\$ @mohammad The code "AR" is the part number code as shown above. The R is the week code. L is the assembly location code. 1S is the assembly lot code. Many of those markings will vary with the batch. This is clearly shown in the document Sam linked. (nb. ARRL does not stand for American Radio Relay League) \$\endgroup\$ Commented Apr 11, 2021 at 17:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.