PNDS / Marking codes / 1A

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

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 19 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
BC846A	PHI	SOT-23	Public marking directory
BC846AS	DIODES	—	Public marking directory
BC846AT	PHI	SOT-416	Public marking directory
BC846AT	PHI	SC-75/ SOT416	Public marking directory
BC846AW	PHI	SOT-323 16ta - 3a PhH	Public marking directory
BC846B	MCC	SOT-23	Public marking directory
BU4341F	ROHM ^*	SOP-4	Public marking directory
BU4341FWE	ROHM ^*	VSOF-5	Public marking directory
BU4341G	ROHM ^*	SSOP-5	Public marking directory
FMMT3904	FERRANTI	SOT-23	Public marking directory
IRLML2402	IR	SOT-23	Public marking directory
KST3904	SMG	SOT-23	Public marking directory
MM5Z47V	FSC	SOD-523	Public marking directory
MMBT3904	FSC	SOT-23	Public marking directory
PXT3904	PHI	SOT-89	Public marking directory
RQ5RW60BA	RICOH ^*	SOT-143R	Public marking directory
SMBT3904	SIEMENS	SOT-23 16ta - 3a Inf	Public marking directory
SXT3904	INFINEON	SOT-89	Public marking directory
YTS3904	TOS	SOT-23	Public marking directory
2T664A9	—	SOT-89	Public marking directory
CMBT3904	—	SOT-23	Public marking directory
MA110	—	SOD-123	Public marking directory
MM3Z47V	—	SOD-323	Public marking directory
R1161D121A5	—	—	Public marking directory
R3132Q20EA	—	SOT-143	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 1B 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.