PNDS / Marking codes / 1B

Identify an unknown SMD part: marking code “1B”

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 21 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
BC846B	NXP	SOT-23 16ta - 3a PhH	Public marking directory
BC846BT	PHI	SOT-416	Public marking directory
BC846BT	PHI	SC-75/ SOT416	Public marking directory
BC846BW	PHI	SOT-323 16ta - 3a PhH	Public marking directory
BC846BW	DIODES	—	Public marking directory
BC847A	MCC	SOT-23	Public marking directory
BU4342F	ROHM ^*	SOP-4	Public marking directory
BU4342FWE	ROHM ^*	VSOF-5	Public marking directory
BU4342G	ROHM ^*	SSOP-5	Public marking directory
FMMT2222	FERRANTI	SOT23	Public marking directory
IRLML2803	IR INTERNATIONAL RECT.	SOT-23	Public marking directory
KST2222	FSC	SOT-23	Public marking directory
MA2J111	PANASONIC	SOT-346	Public marking directory
MMBT2222	ON	SOT-23	Public marking directory
R3111N111A	RICOH ^*	SOT-23-5	Public marking directory
RH5RL21AA	RICOH ^*	SOT-89	Public marking directory
RN5RL21AA	RICOH ^*	SOT-23-5	Public marking directory
RQ5RW19BA	RICOH ^*	SOT-143R	Public marking directory
SMBT2222	SIEMENS	SOT-23 16ta - 3a Inf	Public marking directory
UNRF1A3	PANASONIC ^*	—	Public marking directory
YTS2222	TOS	SOT-23	Public marking directory
2N2222	—	SOT-23	Public marking directory
BC846B9	—	SOT-23	Public marking directory
BC846BDW	—	SOT-363	Public marking directory
R1161D111A	—	—	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 “1”

10 11 12 13 14 15 16 18 1A 1C

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.