PNDS / Marking codes / YJ

Identify an unknown SMD part: marking code “YJ”

Packages rarely print the full part number. The marking below is shared by several part numbers — use the package, pin count and the manufacturer family together to narrow it down, then confirm against the datasheet.

19 candidates 16 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
BCX71RJ	SIEMENS	SOT-23	Public marking directory
BU4217F	ROHM ^*	SOP-4	Public marking directory
BU4217FWE	ROHM ^*	VSOF-5	Public marking directory
BU4217G	ROHM ^*	SSOP-5	Public marking directory
R5325N018A	RICOH ^*	SOT-23-6	Public marking directory
RN2109	TOS	SOT-416	Public marking directory
RN2309	TOS	SOT-346	Public marking directory
RN2409	TOS	SOT-346	Public marking directory
RN2509	TOS	—	Public marking directory
RN2609	TOS	—	Public marking directory
RN2709	TOS	SOT-353	Public marking directory
RN2709JE	TOS	SOT-553	Public marking directory
RN2909	TOS	—	Public marking directory
RN2909FE	TOS	SOT-563	Public marking directory
RN5RK222A	RICOH ^*	SOT-23-5	Public marking directory
SMZJ3805B	VISHAY SEMI	DO-214AA	Public marking directory
CZMK27	—	SOT-23	Public marking directory
R1210N282D	—	SOT-23-5	Public marking directory
SMZG3805B	—	DO-215AA	Public marking directory

How we narrow this down

Package first — SOT-23 vs SOD-123 vs SC-59 eliminates most candidates immediately.
Pin count and body size — a 3-pin SOT-23 LDO cannot be a 6-pin dual transistor.
Marking style — laser-marked parts are usually newer production; ink marking often indicates older or second-source vendors.
Circuits around it — a part sitting on a rail with an inductor is a regulator, not a diode.
Datasheet check — every credible candidate lists its marking scheme in the “marking information” section.

FAQ

Same code, several parts — which one do I actually have? Compare package + pin count + surrounding circuit; if it still fits two parts, request a sample verification before production.
Can I substitute between the candidates? No — the same marking may sit on electrically different parts. Always match the electrical spec sheet, not just the marking.
Where do these mappings come from? Public SMD marking directories and historical stock tables; each row keeps its source so you can trace it.

Other codes starting with “Y”

Y1 Y3 YA YB YC YE YELLOW YF YK YP

Still not sure what the part is?

Send the code, package and a photo through the BOM hub — our engineers cross-check it against datasheets and sourcing records.

How these mappings are compiled: public SMD marking directories plus our own stock records. Each row keeps its original reference internally, so any mapping can be traced on request. ^* Manufacturer derived from the part-number family (some directory entries carry no manufacturer) — treat it as a lead, not a datasheet fact. Markings are indicative only — confirm with the physical batch marking and the original datasheet before ordering.