PNDS / Marking codes / BK

Identify an unknown SMD part: marking code “BK”

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
BCP56-10	PHI	SOT-223	Public marking directory
BCX56-10	PHI	SOT-89	Public marking directory
BCX56-10	PHI	SC-62/SOT89	Public marking directory
BCX71K	FSC	SOT23	Public marking directory
BD4729G	ROHM ^*	—	Public marking directory
BZX399-C11	PHI	SOD-323	Public marking directory
BZX399-C11	PHI	SC-76/SOD323	Public marking directory
BZX399C11	PHI	SOD323	Public marking directory
HSMS-281K	AGILENT	SOT-323	Public marking directory
MAX822RUS-T	MAX ^*	SOT-143	Public marking directory
MMBZ5249B	FSC	SOT-23 16dc - 3a Lge	Public marking directory
MMSZ4684	FSC	SOD-123	Public marking directory
P6SMBJ14AC	LITTLE ^*	DO-214AA	Public marking directory
R3112Q191A	RICOH ^*	SC-82AB	Public marking directory
R5421N149C	RICOH ^*	SOT-23-6	Public marking directory
RN5RT39AA	RICOH ^*	SOT-23-5	Public marking directory
SMF14A	ON	DO-219AB	Public marking directory
UDZ12B	DIODES	SOD-323	Public marking directory
UDZ13B	DIODES	—	Public marking directory
2SB1323	—	PCP	Public marking directory
Anode1	—	—	Public marking directory
BCX56-10R	—	SOT-89	Public marking directory
BZT52H-C11	—	SOD123F	Public marking directory
BZX884-C13	—	SOD-882	Public marking directory
CD214B-T14CA	—	DO-214AA	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.