# BC556

**Changjiang Electronics Tech (CJ)** · Bipolar Transistors - BJT · TO-92

BC556 from Changjiang Electronics Tech (CJ), in a TO-92. 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 | COLLECTOR | passive | Collector; VCBO -80V (BC556), VCEO -65V (BC556), continuous collector current -0.1 A. |
| 2 | BASE | input | Base; emitter-base voltage limit VEBO is -5 V. |
| 3 | EMITTER | passive | Emitter of the PNP transistor; V(BR)EBO is -5 V at IE=-100 µA. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Changjiang Electronics Tech (CJ) |
| Package | TO-92 |
| Category | Transistors |
| 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 Voltage | VCBO |  |  | -80 | V | BC556, Ta=25℃ | 1 |
| Collector-Emitter Voltage | VCEO |  |  | -65 | V | BC556, Ta=25℃ | 1 |
| Emitter-Base Voltage | VEBO |  |  | -5 | V | Ta=25℃ | 1 |
| Collector Current-Continuous | IC |  |  | -0.1 | A | Ta=25℃ | 1 |
| Collector Power Dissipation | PC |  |  | 625 | mW | Ta=25℃ | 1 |
| Thermal Resistance from Junction to Ambient | RθJA |  |  | 200 | ℃/W |  | 1 |
| Junction Temperature | Tj |  |  | 150 | ℃ |  | 1 |
| Storage Temperature | Tstg | -55 |  | 150 | ℃ |  | 1 |
| Collector-base breakdown voltage | V(BR)CBO | -80 |  |  | V | IC= -0.1mA,IE=0, BC556 | 2 |
| Collector-emitter breakdown voltage | V(BR)CEO | -65 |  |  | V | IC=-2mA,IB=0, BC556 | 2 |
| Emitter-base breakdown voltage | V(BR)EBO | -5 |  |  | V | IE=-100μA,IC=0 | 2 |
| Collector cut-off current | ICBO |  |  | -0.1 | μA | VCB=-70V,IE=0, BC556 | 2 |
| Emitter cut-off current | IEBO |  |  | -0.1 | μA | VEB=-5V,IC=0 | 2 |
| DC current gain | hFE | 120 |  | 800 |  | VCE=-5V, IC=-2mA | 2 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | -0.3 | V | IC=-10mA,IB=-0.5mA | 2 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | -0.65 | V | IC=-100mA,IB=-5mA | 2 |
| Base-emitter saturation voltage | VBE(sat) |  |  | -0.8 | V | IC=-10mA,IB=-0.5mA | 2 |
| Base-emitter saturation voltage | VBE(sat) |  |  | -1 | V | IC=-100mA,IB=-5mA | 2 |
| Base-emitter voltage | VBE | -0.55 |  | -0.7 | V | VCE=-5V, IC=-2mA | 2 |
| Base-emitter voltage | VBE |  |  | -0.82 | V | VCE=-5V, IC=-10mA | 2 |
| Collector output capacitance | Cob |  |  | 6 | pF | VCB=-10V,IE=0, f=1MHz | 2 |
| Transition frequency | fT |  | 150 |  | MHz | VCE=-5V,IC=-10mA, f=100MHz, BC556 | 2 |

## CAD (KiCad official)

- Symbol: `BC556`
- Footprint: `Package_TO_SOT_THT:TO-92_Inline`
- 3D model: TO-92 (KiCad packages3D, STEP)
- 3D model files: `bc556-etched.step` / `bc556-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bc556.step` / `bc556.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Changjiang Electronics Tech (CJ) datasheet](docs/bc556-datasheet.pdf) (2 pp, sha256 `ce8dcdd4f2145ae3`, retrieved 2026-10-31, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-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/bc556-datasheet.pdf)