PNDS / Marking codes / M4

Identify an unknown SMD part: marking code “M4”

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 22 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
2SA812-M4	MCC	SOT-23	Public marking directory
2SA812-M5	MCC	SOT-23	Public marking directory
BSR56	FSC	SOT-23	Public marking directory
BZX384-B18	PHI	SOD-323	Public marking directory
CMOZ3L3	CSC CENTRAL SEMIC.CORP.	SOD-523	Public marking directory
KST812-M4	FSC ^*	SOT-23	Public marking directory
MBD110DW	MOT	SOT-363	Public marking directory
MMBA812M4	MOT ^*	SOT-23	Public marking directory
MMBZ5259B	DIODES	SOT-23	Public marking directory
MMBZ5259BW	DIODES	SOT-323	Public marking directory
MMSZ5232B	FSC	SOD-123	Public marking directory
MMSZ5259B	MCC	SOD-123	Public marking directory
MMTT2222A	DIODES	—	Public marking directory
PXT2222A	MCC	SOT-89	Public marking directory
R1121N341A	RICOH ^*	SOT-23-5	Public marking directory
R3111N442C	RICOH ^*	SOT-23	Public marking directory
R3111Q241A	RICOH ^*	SC-82AB	Public marking directory
R3116Q211A	RICOH ^*	SC-82AB	Public marking directory
RN5RG54AA	RICOH ^*	SOT-23-5	Public marking directory
RN5RY441A	RICOH ^*	SOT-23-5	Public marking directory
TC54VN2402ECB	MIC ^*	SOT-23	Public marking directory
TC54VN2402MB	MIC ^*	SOT-89	Public marking directory
2SA1179-4	—	CPA 16ta - 3a San	Public marking directory
2SA1179-M4	—	—	Public marking directory
2SA1611-4	—	SOT-323	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 “M”

MEV MK7 M1 M2 M3 M5 M6 M7 M8 M9

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.