PNDS / Marking codes / 12

Identify an unknown SMD part: marking code “12”

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 13 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
BU4S01G2	ROHM ^*	SSOP-5	Public marking directory
BU4S81G2	ROHM ^*	SSOP-5	Public marking directory
CMZ12	TOS	—	Public marking directory
DTA123EKA	ROHM	SOT-346	Public marking directory
DTA123EUA	ROHM	—	Public marking directory
ESD5V0K5	MCC	SOT-363	Public marking directory
MAZ8120	PANASONIC ^*	SC-76	Public marking directory
MAZS120	PANASONIC ^*	SC-79	Public marking directory
MAZS1200L	PANASONIC ^*	SC-79	Public marking directory
MUN5312DW1	MOT	SOT363	Public marking directory
P6SMBJ12	LITTLE ^*	DO-214AA	Public marking directory
R3111Q121B	RICOH ^*	SC-82AB	Public marking directory
UPA1428AH(1)-AZ	NEC	ZIP-10	Stock-record verified
DTA123EE	—	SOT-416	Public marking directory
DTA123EM	—	—	Public marking directory
KDZ12EV	—	SOD-523	Public marking directory
KDZ12V	—	SOD-323	Public marking directory
MAZ5120	—	—	Public marking directory
MAZW120H	—	—	Public marking directory
MAZY120	—	NMiniP2	Public marking directory
MM3Z27V	—	SOD-323	Public marking directory
MSCT12	—	SOT-23	Public marking directory
MUN5312DW	—	SOT-363	Public marking directory
R1163D221E	—	—	Public marking directory
R1223N502D	—	SOT-23-5	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 “1”

10 11 13 14 15 16 18 1A 1B 1C

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.