# CZT31C

**Changjing** · Bipolar (BJT) · SOT-223

CZT31C from Changjing, in a SOT-223. 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 CZT31C NPN transistor; the datasheet gives VBE of 1.8 V max at VCE=4 V, IC=3 A, and emitter-base breakdown of 5 V min. |
| 2 | COLLECTOR | passive | Collector terminal rated for VCBO and VCEO of 100 V and continuous collector current of 3 A, with VCE(sat) of 1.2 V at IC=3.0 A and IB=375 mA. |
| 3 | EMITTER | passive | Emitter terminal of the NPN device; the datasheet specifies emitter-base voltage VEBO of 5 V and states the part is complementary to CZT32C. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Changjing |
| Package | SOT-223 |
| 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 voltage | VCBO |  |  | 100 | V |  | 1 |
| Collector-emitter voltage | VCEO |  |  | 100 | V |  | 1 |
| Emitter-base voltage | VEBO |  |  | 5 | V |  | 1 |
| Collector current, continuous | IC |  |  | 3 | A |  | 1 |
| Collector power dissipation | PC |  |  | 1 | W |  | 1 |
| Operation junction and storage temperature range | TJ,Tstg | -55 |  | 150 | ℃ |  | 1 |
| Collector-base breakdown voltage | V(BR)CBO | 100 |  |  | V | IC=1mA, IE=0 | 1 |
| Collector-emitter breakdown voltage | V(BR)CEO | 100 |  |  | V | IC=30mA, IB=0 | 1 |
| Emitter-base breakdown voltage | V(BR)EBO | 5 |  |  | V | IE=3mA, IC=0 | 1 |
| Collector cut-off current | ICBO |  |  | 200 | uA | VCB=100V, IE=0 | 1 |
| Base cut-off current | ICEO |  |  | 300 | uA | VCE=60V, IB=0 | 1 |
| Emitter cut-off current | IEBO |  |  | 1 | mA | VEB=5V, IC=0 | 1 |
| DC current gain (hFE(1)) | hFE(1) | 25 |  |  |  | VCE=4V, IC=1A | 1 |
| DC current gain (hFE(2)) | hFE(2) | 10 |  | 100 |  | VCE=4V, IC=3A | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 1.2 | V | IC=3.0A, IB=375mA | 1 |
| Base-emitter voltage | VBE |  |  | 1.8 | V | VCE=4V, IC=3A | 1 |
| Transition frequency | fT | 3 |  |  | MHz | VCE=10V, IC=500mA, f=1MHz | 1 |

## CAD (KiCad official)

- Symbol: `CZT31C`
- Footprint: `Package_TO_SOT_SMD:SOT-223-3_TabPin2`
- 3D model: SOT-223 (KiCad packages3D, STEP)
- 3D model files: `czt31c-etched.step` / `czt31c-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `czt31c.step` / `czt31c.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/8588944431127146496) (4 pp, sha256 `80f563bfeeed236f`, 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/czt31c-datasheet.pdf)