Home / Transistors / 2N3904 / 2N3906 / S8050 Cross Reference
2N3904 / 2N3906 / S8050 cross reference
Industry parts2N3904 · 2N3906 · S8050
Equivalents4 Weforsemi SMD types + TO-92
PackagesSOT-523 · SOT-23 · TO-92
PolaritiesNPN & PNP pairs covered
The 2N3904 (NPN), 2N3906 (PNP) and S8050 (NPN) are the general-purpose transistors that appear on more BOMs than any others in their class, traditionally as TO-92 through-hole parts. Our Weforsemi line stocks surface-mount equivalents for all three lookups, listed below as a cross reference: equivalent replacements matched by polarity, function and package class — not original-manufacturer parts, and not a promise that any specific board works without the checks described here.
One caution matters more with transistors than with diodes: SOT-23 and SOT-523 pin configurations vary between manufacturers. The equivalents below are the standard starting points, and the pinout of the specific part is confirmed against its datasheet before we quote it as a replacement for a named original. Send the full original designation — including any suffix that encodes pinout or gain group — with your enquiry.
Converting a TO-92 position to SMD
The mechanical part is straightforward: SOT-23 and SOT-523 occupy a fraction of the TO-92 footprint and remove a through-hole operation. The electrical part needs the checklist. Polarity and pinout first (see above). Then gain group: the classic parts are binned or specified over wide hFE ranges, and a circuit that depends on a narrow gain band — a biased sensor front end, a matched pair — must be checked against the equivalent's gain specification at your collector current. Then the ratings envelope: collector-emitter voltage and collector current of the equivalent must cover the original's working point with your usual margin, and power dissipation in a small SMD package depends on the copper area the layout provides.
For designs that cannot move to SMD, the cross reference also lists a TO-92 option: the VC2N3906Z is a through-hole PNP part published at 40 V, and the related VC2N4401Z is a TO-92 NPN part published at 600 mA for the adjacent 2N4401-class lookup. Both keep the original assembly process unchanged.
Pairs and complements
The 2N3904 and 2N3906 are normally specified together as a complementary pair, and the equivalents preserve that structure: VC3904TB (NPN, SOT-523) pairs with VC3906B (PNP, SOT-23). The S8050 equivalents split by current class — the VC8050X-0.3A for the standard position and the VCSS8050B-1.5A where the published listing's higher current designation fits the design. Where a circuit uses the pair in a matched or mirrored arrangement, tell us in the enquiry; we will flag whether the equivalents' gain distributions suit it or whether the original parts should be sourced instead.
Cross reference — industry parts to Weforsemi equivalents
| Industry part | Our equivalent | Package | Published data |
|---|---|---|---|
| 2N3904 | VC3904TB | SOT-523 | NPN transistor |
| 2N3906 | VC3906B | SOT-23 | PNP transistor |
| 2N3906 (through-hole) | VC2N3906Z | TO-92 | PNP transistor, 40 V |
| S8050 | VC8050X-0.3A | SOT-23 | NPN transistor |
| S8050 (higher current listing) | VCSS8050B-1.5A | SOT-23 | NPN transistor, 300 mW class |
| 2N4401 class (related) | VC2N4401Z | TO-92 | NPN transistor, 600 mA |
Parameters are quoted from the manufacturer's published product pages. Confirm the full datasheet specification before design-in; ratings are confirmed at quotation.
Questions & answers
Are SOT-23 transistor pinouts standardised?
Not fully — pin configuration varies between manufacturers and sometimes between variants of one part number. That is why we confirm the equivalent's pinout against its datasheet for your exact original designation before quoting a replacement.
Can you supply the original TO-92 2N3904 and 2N3906?
Yes, through the sourcing service, subject to availability; and the Weforsemi line itself includes a TO-92 PNP option (VC2N3906Z). State your preference — original, own-brand through-hole, or SMD equivalent — in the enquiry.
What if my circuit needs a specific gain group?
Say so in the enquiry with the required hFE range and test current. We check the equivalent's published gain specification and tell you whether it covers the band or the original part should be sourced.
See also: Transistors · NPN & PNP transistors · MOSFETs