# BC857BLT3G

**onsemi** · Bipolar (BJT) · SOT-23

BC857BLT3G from onsemi, 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 terminal of the PNP transistor; for BC857 the collector-emitter voltage is limited to -45 V and continuous collector current to -100 mA (absolute maximum ratings, page 2). |
| 2 | EMITTER | passive | Emitter terminal of the PNP transistor; the emitter-base voltage is rated at -5.0 V maximum (absolute maximum ratings, page 2). |
| 3 | COLLECTOR | passive | Collector terminal of the PNP transistor; for BC857 the collector-base voltage is limited to -50 V and continuous collector current to -100 mA (absolute maximum ratings, page 2). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | onsemi |
| 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-Emitter Breakdown Voltage (BC857 series) | V(BR)CEO | -45 |  |  | V | IC = −10 mA | 3 |
| Collector-Emitter Breakdown Voltage (BC857A/BC857B only) | V(BR)CES | -50 |  |  | V | IC = −10 A, VEB = 0 | 3 |
| Collector-Base Breakdown Voltage (BC857 series) | V(BR)CBO | -50 |  |  | V | IC = −10 A | 3 |
| Emitter-Base Breakdown Voltage (BC857 series) | V(BR)EBO | -5 |  |  | V | IE = −1.0 A | 3 |
| Collector Cutoff Current | ICBO |  |  | -15 | nA | VCB = −30 V | 3 |
| Collector Cutoff Current | ICBO |  |  | -4 | µA | VCB = −30 V, TA = 150°C | 3 |
| DC Current Gain (BC857B) | hFE | 220 | 290 | 475 |  | IC = −2.0 mA, VCE = −5.0 V | 3 |
| Collector-Emitter Saturation Voltage | VCE(sat) |  |  | -0.3 | V | IC = −10 mA, IB = −0.5 mA | 3 |
| Collector-Emitter Saturation Voltage | VCE(sat) |  |  | -0.65 | V | IC = −100 mA, IB = −5.0 mA | 3 |
| Base-Emitter On Voltage | VBE(on) | -0.6 |  | -0.75 | V | IC = −2.0 mA, VCE = −5.0 V | 3 |
| Base-Emitter On Voltage | VBE(on) |  |  | -0.82 | V | IC = −10 mA, VCE = −5.0 V | 3 |
| Current-Gain - Bandwidth Product | fT | 100 |  |  | MHz | IC = −10 mA, VCE = −5.0 Vdc, f = 100 MHz | 3 |
| Output Capacitance | Cob |  |  | 4.5 | pF | VCB = −10 V, f = 1.0 MHz | 3 |
| Noise Figure (BC857 series) | NF |  |  | 10 | dB | IC = −0.2 mA, VCE = −5.0 Vdc, RS = 2.0 k, f = 1.0 kHz, BW = 200 Hz | 3 |
| Base-Emitter Saturation Voltage | VBE(sat) |  | -0.7 |  | V | IC = −10 mA, IB = −0.5 mA | 3 |
| Base-Emitter Saturation Voltage | VBE(sat) |  | -0.9 |  | V | IC = −100 mA, IB = −5.0 mA | 3 |
| Collector-Emitter Voltage (BC857 series) | VCEO |  |  | -45 | V |  | 2 |
| Collector-Base Voltage (BC857 series) | VCBO |  |  | -50 | V |  | 2 |
| Emitter-Base Voltage | VEBO |  |  | -5 | V |  | 2 |
| Collector Current - Continuous | IC |  |  | -100 | mAdc |  | 2 |
| Collector Current - Peak | IC |  |  | -200 | mAdc |  | 2 |
| Total Device Dissipation (FR-5 board) | PD |  |  | 225 | mW | FR-5 Board (Note 1), TA = 25°C | 2 |
| Total Device Dissipation (alumina substrate) | PD |  |  | 300 | mW | Alumina Substrate (Note 2), TA = 25°C | 2 |
| Thermal Resistance, Junction-to-Ambient (FR-5 board) | RθJA |  |  | 556 | °C/W | FR-5 Board (Note 1) | 2 |
| Thermal Resistance, Junction-to-Ambient (alumina substrate) | RθJA |  |  | 417 | °C/W | Alumina Substrate (Note 2) | 2 |
| Junction and Storage Temperature | TJ, Tstg | -55 |  | 150 | °C |  | 2 |

## CAD (KiCad official)

- Symbol: `BC857BLT3G`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `bc857blt3g-etched.step` / `bc857blt3g-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bc857blt3g.step` / `bc857blt3g.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [onsemi datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8588928983459377152) (9 pp, sha256 `daeab23fa6c6ac7c`, retrieved 2026-10-09, 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/bc857blt3g-datasheet.pdf)