PNDS / Marking codes / F1

Identify an unknown SMD part: marking code “F1”

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
BFS18	PHI	SOT23	Public marking directory
CMOZ2V4	CSC CENTRAL SEMIC.CORP. ^*	SOD-523	Public marking directory
HSMP-3821	HP	SOT23	Public marking directory
KST1009-F1	FSC ^*	SOT-23	Public marking directory
MMBC1009F1	MOT	SOT-23	Public marking directory
MMBZ5236B	FSC	SOT-23	Public marking directory
MMBZ5236BW	DIODES	SOT-323	Public marking directory
MMSZ5236B	MCC	SOD-123	Public marking directory
MMSZ5236BS	DIODES	SOD-323	Public marking directory
MMSZ5236BS	DIODES	—	Public marking directory
MMSZ5237B	DIODES	—	Public marking directory
MMXZ5237B	MCC	SOD-323	Public marking directory
R3111N512A	RICOH ^*	SOT-23	Public marking directory
R3113D211C	RICOH ^*	—	Public marking directory
R3114Q081C	RICOH ^*	SC-82AB	Public marking directory
R5421N162C	RICOH ^*	SOT-23-6	Public marking directory
TC1073-2.5VCH	MIC ^*	SOT-23-6	Public marking directory
TC54VC5102ECB	MIC ^*	SOT-23	Public marking directory
TC54VC5102MB	MIC ^*	SOT-89	Public marking directory
BZX585-C2V4	—	SOD-523	Public marking directory
ELM7621HBB	—	SOT-23 16vdc VD7 3d Elm	Public marking directory
ELM9751NAB	—	SOT-89	Public marking directory
FFM101-MH	—	SOD-123H	Public marking directory
FRS1A	—	DO-214AC	Public marking directory
Gate1	—	—	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 “F”

F F0 F2 F3 F4 F5 F6 F7 F8 F9

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.