# BC857T

**Changjing** · Bipolar (BJT) · SOT-523

BC857T from Changjing, in a SOT-523. 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 BC857T PNP transistor; the datasheet's absolute emitter-base voltage rating (VEBO) is -6 V. |
| 2 | EMITTER | passive | Emitter terminal of the BC857T PNP transistor; the datasheet's absolute emitter-base voltage rating (VEBO) is -6 V. |
| 3 | COLLECTOR | passive | Collector terminal of the BC857T PNP transistor; the datasheet gives a collector-emitter voltage (VCEO) of -45 V and continuous collector current of -0.1 A. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Changjing |
| Package | SOT-523 |
| 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 | -50 |  |  | V | IC= -10µA, IE=0 | 1 |
| Collector-emitter breakdown voltage | V(BR)CEO | -45 |  |  | V | IC= -10mA, IB=0 | 1 |
| Emitter-base breakdown voltage | V(BR)EBO | -6 |  |  | V | IE= -1µA, IC=0 | 1 |
| Collector cutoff current | ICBO |  |  | -15 | nA | VCB=-30V | 1 |
| DC current gain | hFE | 125 |  | 800 |  | VCE=-5V, IC=-2mA | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | -0.3 | V | IC=-10mA, IB=-0.5 mA | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | -0.65 | V | IC=-100mA, IB=-5 mA | 1 |
| Base-emitter saturation voltage | VBE(sat) |  |  | -0.7 | V | IC=-10mA, IB=-0.5 mA | 1 |
| Base-emitter saturation voltage | VBE(sat) |  |  | -0.9 | V | IC=-100mA, IB= -5 mA | 1 |
| Base-emitter voltage | VBE(on) | -600 |  | -750 | mV | VCE= -5V, IC= -2mA | 1 |
| Base-emitter voltage | VBE(on) |  |  | -820 | mV | VCE= -5V, IC= -10mA | 1 |
| Transition frequency | fT | 100 |  |  | MHz | VCE= -5 V, IC= -10mA, f=100MHz | 1 |
| Collector output capacitance | Cob |  |  | 4.5 | pF | VCB=-10V, f=1MHz | 1 |
| Noise figure | NF |  |  | 10 | dB | VCE=-5V, IC=-0.2mA, f=1kHz, RS=2kΩ, BW=200Hz | 1 |
| Operation junction and storage temperature range | TJ,Tstg | -55 |  | 150 | ℃ |  | 1 |
| Collector-base voltage | VCBO |  |  | -50 | V |  | 1 |
| Collector-emitter voltage | VCEO |  |  | -45 | V |  | 1 |
| Emitter-base voltage | VEBO |  |  | -6 | V |  | 1 |
| Collector current, continuous | IC |  |  | -0.1 | A |  | 1 |
| Collector power dissipation | PC |  |  | 150 | mW |  | 1 |

## CAD (KiCad official)

- Symbol: `BC857T`
- Footprint: `Package_TO_SOT_SMD:SOT-523`
- 3D model: SOT-523, generated from the KiCad footprint (body from the F.Fab outline, terminals on the pads, 0.8 mm nominal SOT-523 height). Neither the vendor nor KiCad ships a 3D model for this package, so the dimensions are nominal, not the manufacturer's CAD (STEP)
- 3D model files: `bc857t-etched.step` / `bc857t-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bc857t.step` / `bc857t.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/8590919950385434624) (4 pp, sha256 `acd5b537693be1c2`, retrieved 2026-10-17, 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/bc857t-datasheet.pdf)