PNDS / Marking codes / BB

Identify an unknown SMD part: marking code “BB”

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 20 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
1SV128	TOS	SOT-23	Public marking directory
1SV237	TOS	SOT-143	Public marking directory
A51	PHI	SOT-23-5	Public marking directory
BAR81	INFINEON	SOT143	Public marking directory
BCW61B	NSC	SOT-23	Public marking directory
BCX54-6	INFINEON	SOT-89	Public marking directory
BD4720G	ROHM ^*	—	Public marking directory
BZT52H-C5V1	PHI	SOD123F	Public marking directory
BZX399-C5V1	PHI	SOD-323	Public marking directory
BZX399-C5V1	PHI	SC-76/SOD323	Public marking directory
BZX399C5V1	PHI	SOD323	Public marking directory
MAX821TUS-T	MAX ^*	SOT-143	Public marking directory
MMBZ5242B	FSC	SOT-23 16dc - 3a Lge	Public marking directory
PI74STX1G126CX	PERICOM	SC-70-5	Public marking directory
PI74STX1G126TX	PERICOM ^*	SOT-23-5	Public marking directory
R3112Q111A	RICOH ^*	SC-82AB	Public marking directory
R5421N139F	RICOH ^*	SOT-23-6	Public marking directory
RN5RT31AA	RICOH ^*	SOT-23-5	Public marking directory
UDZ5V1B	DIODES	SOD-323	Public marking directory
UDZ5V6B	DIODES	—	Public marking directory
2SB831-B	—	MPAK 16ta - 3a Hit	Public marking directory
2SD1367-B	—	SOT-89	Public marking directory
2SD1367-BB	—	SOT-89	Public marking directory
A31	—	SOT-23-5	Public marking directory
A32A	—	—	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.