PNDS / Marking codes / BJ

Identify an unknown SMD part: marking code “BJ”

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.

25 candidates 13 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
BCX56-6	INFINEON	SOT-89	Public marking directory
BCX71J	FSC	SOT-23	Public marking directory
BD4728G	ROHM ^*	—	Public marking directory
BZX399-C10	PHI	SOD-323	Public marking directory
BZX399-C10	PHI	SC-76/SOD323	Public marking directory
BZX399C10	NXP	SOD323	Public marking directory
MAX822SUS-T	MAX	SOT-143	Public marking directory
MMBZ5248B	FSC	SOT-23 16dc - 3a Lge	Public marking directory
R3112Q181A	RICOH ^*	SC-82AB	Public marking directory
R5421N161C	RICOH ^*	SOT-23-6	Public marking directory
RN5RT38AA	RICOH ^*	SOT-23-5	Public marking directory
UDZ11B	DIODES	SOD-323	Public marking directory
UDZ12B	DIODES	—	Public marking directory
2SB1001-J	—	SOT-89	Public marking directory
Anode1	—	—	Public marking directory
BCX56-06	—	SOT-89	Public marking directory
BZT52H-C10	—	SOD123F	Public marking directory
BZX884-C12	—	SOD-882	Public marking directory
ELM99381B	—	SOT-89	Public marking directory
KTD1302	—	SOT-89	Public marking directory
MMSZ4683	—	SOD-123	Public marking directory
R1141Q281B	—	SOT-143R	Public marking directory
RP130Q281A5	—	SC-82AB	Public marking directory
RT9169-29CV	—	SOT-23	Public marking directory
RT9169-29CX	—	SOT-89	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 “B”

B1 B2 B3 B4 B5 B6 B7 B8 B9 BA

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.