Identify an unknown SMD part: marking code “C21B”
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.
5 candidates 1 with manufacturer source-traceable
Candidate part numbers
| Part number | Manufacturer | Package | Mapping source |
|---|
| R1173S211B | RICOH * | — | Public marking directory |
| ML61C212M | — | SOT-23 16vdb VD7 3a Mlc | Public marking directory |
| ML61C212P | — | SOT-89 | Public marking directory |
| R1130D211B | — | — | Public marking directory |
| R1130H211B | — | SOT-89-5 | 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 “C”
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.