PNDS / Marking codes / 5B

Identify an unknown SMD part: marking code “5B”

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 15 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
BC807-25	NXP	SOT-23	Public marking directory
BC807-25W	NXP	SOT-323 16ta - 3a PhH	Public marking directory
BC807-25W	DIODES	—	Public marking directory
BC807-40	MCC	SOT-23	Public marking directory
FMMD6100	FERRANTI	SOT-23	Public marking directory
KST4123	FSC	SOT-23	Public marking directory
MM1Z10	SEMTECH	SOD-123	Public marking directory
MMBD6100	MCC	SOT23	Public marking directory
MMBT4123	MOT	SOT-23	Public marking directory
MMSZ10	ON ^*	SOD-123	Public marking directory
R3111N151A	RICOH ^*	SOT-23-5	Public marking directory
RH5RL25AA	RICOH ^*	SOT-89	Public marking directory
RN5RL25AA	RICOH ^*	SOT-23-5	Public marking directory
RQ5RW51AA	RICOH ^*	SOT-143R	Public marking directory
UMZ13K	ROHM ^*	SOT-343	Public marking directory
2SC5938-B	—	SC-59	Public marking directory
2SC5996-B	—	SC-70	Public marking directory
LBC807-25LT1	—	SOT-23	Public marking directory
R1161D151A	—	—	Public marking directory
R3131N25EC	—	SOT-23	Public marking directory
R3132Q11EC	—	SOT-143	Public marking directory
RN5VD15CA	—	SOT-23-5	Public marking directory
TCMM5Z6V8	—	SOD-523	Public marking directory
VD6	—	—	Public marking directory
VD7	—	—	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 “5”

51 5A 5C 5D 52 5H 55 56 5E 5F

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.