# KTC4373

**Changjing** · Bipolar (BJT) · SOT-89-3L

KTC4373 from Changjing, in a SOT-89-3L. 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 | NPN transistor base terminal; the datasheet's maximum ratings table lists VEBO 5 V and the emitter-base breakdown voltage is 5 V minimum at IE=1mA. |
| 2 | COLLECTOR | passive | NPN transistor collector terminal; rated for VCBO 120 V, VCEO 120 V, and collector current IC 800 mA with collector power dissipation PC 500 mW. |
| 3 | EMITTER | passive | NPN transistor emitter terminal; the emitter-base voltage rating VEBO is 5 V and the emitter cut-off current is 100 nA max at VEB=5V. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Changjing |
| Package | SOT-89-3L |
| 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 | 120 |  |  | V | IC= 1mA,IE=0 | 1 |
| Collector-emitter breakdown voltage | V(BR)CEO | 120 |  |  | V | IC=10mA,IB=0 | 1 |
| Emitter-base breakdown voltage | V(BR)EBO | 5 |  |  | V | IE=1mA,IC=0 | 1 |
| Collector cut-off current | ICBO |  |  | 100 | nA | VCB=120V,IE=0 | 1 |
| Emitter cut-off current | IEBO |  |  | 100 | nA | VEB=5V,IC=0 | 1 |
| DC current gain | hFE | 80 |  | 240 |  | VCE=5V, IC=100mA | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 1 | V | IC=500mA,IB=50mA | 1 |
| Base-emitter voltage | VBE |  |  | 1 | V | VCE=5V, IC=500mA | 1 |
| Collector output capacitance | Cob |  |  | 30 | pF | VCB=10V,IE=0, f=1MHz | 1 |
| Transition frequency | fT |  | 120 |  | MHz | VCE=5V,IC= 500mA | 1 |
| Collector-base voltage | VCBO |  |  | 120 | V |  | 1 |
| Collector-emitter voltage | VCEO |  |  | 120 | V |  | 1 |
| Emitter-base voltage | VEBO |  |  | 5 | V |  | 1 |
| Collector current | IC |  |  | 800 | mA |  | 1 |
| Collector power dissipation | PC |  |  | 500 | mW |  | 1 |
| Junction temperature | Tj |  |  | 150 | ℃ |  | 1 |
| Storage temperature | Tstg | -55 |  | 150 | ℃ |  | 1 |
| Thermal resistance, junction to ambient | RθJA |  |  | 250 | ℃/W |  | 1 |

## CAD (KiCad official)

- Symbol: `KTC4373`
- Footprint: `Package_TO_SOT_SMD:SOT-89-3`
- 3D model: SOT-89-3L (KiCad packages3D, STEP)
- 3D model files: `ktc4373-etched.step` / `ktc4373-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ktc4373.step` / `ktc4373.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/8586174132534435840) (1 pp, sha256 `fb7b61e01e4397b3`, retrieved 2026-10-19, 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/ktc4373-datasheet.pdf)