# BC857 3E

**Changjing** · Bipolar (BJT) · SOT-23

BC857 3E from Changjing, in a SOT-23. 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 lead of the BC857 PNP transistor; the datasheet rates the emitter-base voltage at -5 V and the continuous collector current at -0.1 A. |
| 2 | EMITTER | passive | Emitter lead of the BC857 PNP transistor; the datasheet rates the emitter-base voltage at -5 V and the continuous collector current at -0.1 A. |
| 3 | COLLECTOR | passive | Collector lead of the BC857 PNP transistor; the datasheet rates the collector-emitter voltage at -45 V for BC857 and the continuous collector current at -0.1 A. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Changjing |
| Package | SOT-23 |
| 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 (BC857) | VCBO | -50 |  |  | V | IC= -10μA, IE=0 | 2 |
| Collector-emitter breakdown voltage (BC857) | VCEO | -45 |  |  | V | IC= -10mA, IB=0 | 2 |
| Emitter-base breakdown voltage | VEBO | -5 |  |  | V | IE= -1μA, IC=0 | 2 |
| Collector cut-off current (BC857) | ICBO |  |  | -0.1 | μA | VCB= -45 V, IE=0 | 2 |
| Emitter cut-off current | IEBO |  |  | -0.1 | μA | VEB= -5 V, IC=0 | 2 |
| DC current gain (BC857A) | hFE | 125 |  | 250 |  | VCE= -5V, IC= -2mA | 2 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | -0.5 | V | IC=-100mA, IB= -5 mA | 2 |
| Base-emitter saturation voltage | VBE(sat) |  |  | -1.1 | V | IC= -100mA, IB= -5mA | 2 |
| Transition frequency | fT | 100 |  |  | MHz | VCE= -5 V, IC= -10mA, f=100MHz | 2 |
| Collector capacitance | Cob |  |  | 4.5 | pF | VCB=-10V, f=1MHz | 2 |
| Collector-base voltage (BC857) | VCBO |  |  | -50 | V |  | 1 |
| Collector-emitter voltage (BC857) | VCEO |  |  | -45 | V |  | 1 |
| Emitter-base voltage | VEBO |  |  | -5 | V |  | 1 |
| Collector current continuous | IC |  |  | -0.1 | A |  | 1 |
| Collector power dissipation | PC |  |  | 200 | mW | Ta=25℃ | 1 |
| Operation junction and storage temperature range | TJ,Tstg | -55 |  | 150 | ℃ |  | 1 |
| Thermal resistance from junction to ambient | RΘJA |  |  | 625 | ℃/W |  | 1 |

## CAD (KiCad official)

- Symbol: `BC857 3E`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `bc857-3e-etched.step` / `bc857-3e-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bc857-3e.step` / `bc857-3e.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/8603161371815669760) (5 pp, sha256 `861906e9f22d0845`, 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/bc857-3e-datasheet.pdf)