MMBT3904

@@ -0,0 +1,48 @@+# MMBT3904++**Diodes Incorporated** · NPN bipolar transistor · SOT-23++Surface-mount NPN small-signal bipolar junction transistor in a SOT-23 package, the SMD counterpart of the 2N3904. Rated for 40 V collector-emitter, 200 mA collector current, with a DC current gain of 100-300 at 10 mA and a 300 MHz transition frequency. Suited to general-purpose amplification and switching. Package marking is K1N.++## Pinout++| Pin | Name | Type | Function |+|---|---|---|---|+| 1 | B | input | Base terminal of the NPN BJT. Controls collector current via base drive; VBE(sat) = 0.65-0.95V at IC = 10-50mA. Emitter-Base breakdown voltage BVEBO = 6.0V. |+| 2 | E | passive | Emitter terminal of the NPN BJT. Typically tied to circuit common or emitter-degeneration network. Emitter-Base breakdown voltage BVEBO = 6.0V. |+| 3 | C | passive | Collector terminal of the NPN BJT. Collector-Emitter breakdown BVCEO = 40V, Collector-Base breakdown BVCBO = 60V, max collector current IC = 200mA. |++## Key specifications++| Parameter | Value |+|---|---|+| Type | NPN small-signal BJT |+| Collector-emitter voltage (VCEO) | 40 V |+| Collector-base voltage (VCBO) | 60 V |+| Emitter-base voltage (VEBO) | 6 V |+| Collector current (IC) | 200 mA |+| DC current gain (hFE) | 100-300 @ IC = 10 mA |+| Transition frequency (fT) | 300 MHz |+| Package | SOT-23 |+| Body (L×W×H) | 2.9 × 1.3 × 1.1 mm |++## Ordering variants++- `MMBT3904-7-F`+- `MMBT3904-13-F`++## CAD (KiCad official)++- Symbol: `Transistor_BJT:MMBT3904`+- Footprint: `Package_TO_SOT_SMD:SOT-23`+- 3D model: SOT-23 (KiCad packages3D)++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [Diodes Incorporated datasheet](https://www.diodes.com/assets/Datasheets/MMBT3904.pdf) (7 pp, sha256 `483284b10e2a58c8`, retrieved 2026-08-17, tier: manufacturer)+- **Extractor:** `ds2sf` (Claude) — every pin and dimension is cited to a datasheet page; refuses to fabricate.+- **CAD:** KiCad official libraries (CC-BY-SA 4.0).++[Datasheet PDF](docs/mmbt3904-datasheet.pdf)

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