# C945

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

C945 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 | input | Base terminal of the NPN transistor; the datasheet specifies VBE(sat) of 1 V at IC=100 mA with IB=10 mA and an emitter-base breakdown of 5 V minimum (VEBO 5 V maximum rating). |
| 2 | EMITTER | passive | Emitter terminal of the NPN transistor; the emitter-base voltage rating VEBO is 5 V and the absolute maximum IC is 150 mA continuous. |
| 3 | COLLECTOR | passive | Collector terminal of the NPN transistor; ratings are VCBO 60 V, VCEO 50 V, continuous IC 150 mA, and collector power dissipation PC 200 mW. |

## 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 | V(BR)CBO | 60 |  |  | V | IC=100uA, IE=0 | 1 |
| Collector-emitter breakdown voltage | V(BR)CEO | 50 |  |  | V | IC=1mA, IB=0 | 1 |
| Emitter-base breakdown voltage | V(BR)EBO | 5 |  |  | V | IE=0.1mA, IC=0 | 1 |
| Collector cut-off current | ICBO |  |  | 0.1 | uA | VCB=60V, IE=0 | 1 |
| Emitter cut-off current | IEBO |  |  | 0.1 | uA | VEB=5V, IC=0 | 1 |
| DC current gain | hFE(1) | 130 |  | 400 |  | VCE=6V, IC=1mA | 1 |
| DC current gain | hFE(2) | 40 |  |  |  | VCE=6V, IC=0.1mA | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 0.3 | V | IC=100mA, IB=10mA | 1 |
| Base-emitter saturation voltage | VBE(sat) |  |  | 1 | V | IC=100mA, IB=10mA | 1 |
| Transition frequency | fT | 150 |  |  | MHz | VCE=6V, IC=10mA, f=30 MHz | 1 |
| Collector output capacitance | Cob |  |  | 3 | pF | VCB=10V, IE=0, f=1MHZ | 1 |
| Noise figure | NF |  | 4 | 10 | dB | VCE=6V, IC=0.1mA, Rg=10kΩ, f=1kMHZ | 1 |
| Collector-base voltage | VCBO |  |  | 60 | V |  | 1 |
| Collector-emitter voltage | VCEO |  |  | 50 | V |  | 1 |
| Emitter-base voltage | VEBO |  |  | 5 | V |  | 1 |
| Collector current, continuous | IC |  |  | 150 | mA |  | 1 |
| Collector power dissipation | PC |  |  | 200 | mW |  | 1 |
| Junction temperature | TJ |  |  | 150 | ℃ |  | 1 |
| Storage temperature | Tstg | -55 |  | 150 | ℃ |  | 1 |

## CAD (KiCad official)

- Symbol: `C945`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `c945-etched.step` / `c945-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `c945.step` / `c945.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/8586172879486115840) (2 pp, sha256 `8d46f71c7d0d0124`, 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/c945-datasheet.pdf)