# 2SC4081

**Changjing** · Bipolar (BJT) · SOT-323

2SC4081 from Changjing, in a SOT-323. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | BASE | input | Base terminal of the NPN transistor; the datasheet gives VEBO of 7 V and a maximum collector current IC of 150 mA, with base-emitter behaviour characterised up to 150 mA in the typical curves. |
| 2 | EMITTER | passive | Emitter terminal of the NPN transistor; the datasheet limits VEBO to 7 V and VCEO to 50 V with a maximum collector current of 150 mA. |
| 3 | COLLECTOR | passive | Collector terminal of the NPN transistor; the datasheet limits VCBO to 60 V, VCEO to 50 V, and collector power dissipation to 200 mW. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Changjing |
| Package | SOT-323 |
| Category | Transistors/Thyristors |
| Pins | 3 |

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Collector-base breakdown voltage | V(BR)CBO | 60 |  |  | V | IC=50μA,IE=0 | 1 |
| Collector-emitter breakdown voltage | V(BR)CEO | 50 |  |  | V | IC=1mA,IB=0 | 1 |
| Emitter-base breakdown voltage | V(BR)EBO | 7 |  |  | V | IE=50μA,IC=0 | 1 |
| Collector cut-off current | ICBO |  |  | 0.1 | μA | VCB=60V,IE=0 | 1 |
| Emitter cut-off current | IEBO |  |  | 0.1 | μA | VEB=7V,IC=0 | 1 |
| DC current gain | hFE(1) | 120 |  | 560 |  | VCE=6V,IC=1mA | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 0.4 | V | IC=50mA,IB=5mA | 1 |
| Transition frequency | fT |  | 180 |  | MHz | VCE=12V,IC=2mA,f=30MHz | 1 |
| Collector output capacitance | Cob |  |  | 3.5 | pF | VCB12V,IE=0,f=1MHz | 1 |
| Collector-base voltage | VCBO |  |  | 60 | V |  | 1 |
| Collector-emitter voltage | VCEO |  |  | 50 | V |  | 1 |
| Emitter-base voltage | VEBO |  |  | 7 | V |  | 1 |
| Collector current, continuous | IC |  |  | 150 | mA |  | 1 |
| Collector power dissipation | PC |  |  | 200 | mW |  | 1 |
| Junction temperature | TJ |  |  | 150 | ℃ |  | 1 |
| Storage temperature | Tstg | -55 |  | 150 | ℃ |  | 1 |

## CAD (KiCad official)

- Symbol: `2SC4081`
- Footprint: `Package_TO_SOT_SMD:SOT-323_SC-70`
- 3D model: SOT-323 (KiCad packages3D, STEP)
- 3D model files: `2sc4081-etched.step` / `2sc4081-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `2sc4081.step` / `2sc4081.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [Changjing datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8586173266406330368) (2 pp, sha256 `13a2624ae88b21a9`, retrieved 2026-10-18, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-haiku-5-5` (text), consensus `claude-sonnet-5-5` (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/2sc4081-datasheet.pdf)