# BC857W

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

BC857W 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 | passive | Base terminal of the PNP transistor; the datasheet gives no pin-specific limit, and the emitter-base voltage is limited to VEBO = -5 V in the maximum ratings. |
| 2 | EMITTER | passive | Emitter terminal of the PNP transistor; emitter-base voltage is limited to VEBO = -5 V and emitter current follows the -0.1 A continuous collector current rating. |
| 3 | COLLECTOR | passive | Collector terminal of the PNP transistor; collector-emitter voltage is rated -65 V (BC856W), -45 V (BC857W) or -30 V (BC858W), and continuous collector current is -0.1 A. |

## 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 (BC857W) | VCBO | -50 |  |  | V | IC= -10μA, IE=0 | 2 |
| Collector-emitter breakdown voltage (BC857W) | VCEO | -45 |  |  | V | IC= -10mA, IB=0 | 2 |
| Emitter-base breakdown voltage | VEBO | -5 |  |  | V | IE= -1μA, IC=0 | 2 |
| DC current gain (BC857AW) | hFE | 125 |  | 250 |  | VCE= -5V, IC= -2mA | 2 |
| DC current gain (BC857BW) | hFE | 220 |  | 475 |  | VCE= -5V, IC= -2mA | 2 |
| DC current gain (BC857CW) | hFE | 420 |  | 800 |  | VCE= -5V, IC= -2mA | 2 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | -0.65 | V | IC=-100mA, IB= -5mA | 2 |
| Base-emitter saturation voltage | VBE(sat) |  |  | -1.1 | V | IC=-100mA, IB= -5mA | 2 |
| Collector cut-off current | ICBO |  |  | -15 | nA | VCB= -30 V, IE=0 | 2 |
| Collector capacitance | Cob |  |  | 4.5 | pF | VCB=-10V, f=1MHz | 2 |
| Transition frequency | fT | 100 |  |  | MHz | VCE= -5V, IC= -10mA, f=100MHz | 2 |
| Collector-base voltage (BC857W) | VCBO | -50 |  |  | V |  | 1 |
| Collector-emitter voltage (BC857W) | VCEO | -45 |  |  | V |  | 1 |
| Emitter-base voltage | VEBO | -5 |  |  | V |  | 1 |
| Collector current, continuous | IC | -0.1 |  |  | A |  | 1 |
| Collector power dissipation | PC* |  |  | 150 | mW |  | 1 |
| Junction temperature | TJ |  |  | 150 | ℃ |  | 1 |
| Storage temperature | Tstg | -65 |  | 150 | ℃ |  | 1 |

## CAD (KiCad official)

- Symbol: `BC857W`
- Footprint: `Package_TO_SOT_SMD:SOT-323_SC-70`
- 3D model: SOT-323 (KiCad packages3D, STEP)
- 3D model files: `bc857w-etched.step` / `bc857w-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bc857w.step` / `bc857w.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/8588881290100031488) (2 pp, sha256 `bdb5a7c12720a101`, 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/bc857w-datasheet.pdf)