PNDS / Marking codes / JS

Identify an unknown SMD part: marking code “JS”

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.

22 candidates 14 with manufacturer source-traceable

Candidate part numbers

Part number	Manufacturer	Package	Mapping source
2SD2532	PANASONIC ^*	SOT-89	Public marking directory
BAS21	FSC	SOT-23	Public marking directory
BAS21A	MCC	SOT-23	Public marking directory
BAS21H	PHI	SOD-323	Public marking directory
BAS21S	INFINEON	SOT-23	Public marking directory
BAS221	NXP	SOD-110	Public marking directory
BAS221	PHI	SOT23	Public marking directory
BAS40	MCC	SOT-23	Public marking directory
BAW100	INFINEON	SOT143	Public marking directory
BU4909F	ROHM ^*	SOP-4	Public marking directory
BU4909FWE	ROHM ^*	VSOF-5	Public marking directory
BU4909G	ROHM ^*	SSOP-5	Public marking directory
MAX6315US29D4-T	MAX ^*	SOT-143	Public marking directory
MIC810SU	MICREL	SOT-23	Public marking directory
AP1115AY-33	—	SOT-89	Public marking directory
AP1115BY-33	—	SOT-89	Public marking directory
ETC810SU	—	SOT-23	Public marking directory
MMSD103	—	SOD-123	Public marking directory
P4SMAJ43	—	DO-214AC	Public marking directory
PT7M6218CLC4	—	SC-70-4	Public marking directory
PT7M6218CLC4E	—	SC-70-4	Public marking directory
RT9166-28CXL	—	SOT-89	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 “J”

J1 J2 J3 J5 JC JJ J4 JE J6 J8

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.