PNDS / Marking codes / D4

Identify an unknown SMD part: marking code “D4”

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 20 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
2SA1252-4	TOS ^*	SOT-23	Public marking directory
AZ23C3V6	DIODES	SOT-23	Public marking directory
BCW31R	PHI	SOT-23R	Public marking directory
HSMP-3804	AGILENT	SOT-23	Public marking directory
MMBD4148SE	FS	SOT-23	Public marking directory
MMBD4148TW	MCC	SOT-363	Public marking directory
MMBZ5229B	FSC	SOT-23	Public marking directory
MMBZ5229BW	DIODES	SOT-323	Public marking directory
MMSZ5226B	FSC	SOD-123	Public marking directory
MMSZ5229B	FSC	SOD-123	Public marking directory
R3111N342A	RICOH ^*	SOT-23	Public marking directory
R3113D441A	RICOH ^*	—	Public marking directory
R3114Q411A	RICOH ^*	SC-82AB	Public marking directory
RN2905AFS	TOS ^*	—	Public marking directory
RN5VD34AA	RICOH ^*	SOT-23-5	Public marking directory
SBR1U150SA	DIODES	—	Public marking directory
SBR2A30P1	DIODES	—	Public marking directory
TC1055-3.3VCT713	MIC	SOT-23-5	Public marking directory
TC54VC3402ECB	MIC ^*	SOT-23	Public marking directory
TC54VC3402MB	MIC ^*	SOT-89	Public marking directory
3T110AB	—	DO-214AA	Public marking directory
AP131-45TW	—	—	Public marking directory
AP131-45W	—	SOT-23-5L	Public marking directory
AP131-45Y	—	SOT-89-5L	Public marking directory
AX1110R33	—	SOT-23L 16vl VR1 3b Axl	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 “D”

D0 D1 D2 D3 D5 D6 D7 D8 D9 DA

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.