# KTC4378

**Changjiang Electronics Tech (CJ)** · Bipolar Transistors - BJT · SOT-89-3L

KTC4378 from Changjiang Electronics Tech (CJ), 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 | Base terminal of the NPN transistor; the base-emitter saturation voltage VBE(sat) is 1.2 V at IC=500mA, IB=50mA. |
| 2 | COLLECTOR | passive | Collector terminal; the datasheet rates VCBO at 80 V, VCEO at 60 V and continuous collector current IC at 1 A. |
| 3 | EMITTER | passive | Emitter terminal; the datasheet rates VEBO at 5 V and the emitter-base breakdown voltage V(BR)EBO at 5 V at IE=1mA. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Changjiang Electronics Tech (CJ) |
| Package | SOT-89-3L |
| 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-Emitter Voltage | VCEO |  |  | 60 | V | Ta=25℃ | 1 |
| Collector-Base Voltage | VCBO |  |  | 80 | V | Ta=25℃ | 1 |
| Emitter-Base Voltage | VEBO |  |  | 5 | V | Ta=25℃ | 1 |
| Collector Current -Continuous | IC |  |  | 1 | A | Ta=25℃ | 1 |
| Collector Dissipation | PC |  |  | 0.5 | W | Ta=25℃ | 1 |
| Junction Temperature | TJ |  |  | 150 | ℃ |  | 1 |
| Storage Temperature | Tstg | -55 |  | 150 | ℃ |  | 1 |
| Collector-base breakdown voltage | V(BR)CBO | 80 |  |  | V | IC=1mA,IE=0 | 1 |
| Collector-emitter breakdown voltage | V(BR)CEO | 60 |  |  | 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 |  |  | 0.1 | μA | VCB=50V,IE=0 | 1 |
| Emitter cut-off current | IEBO |  |  | 0.1 | μA | VEB=4V,IC=0 | 1 |
| DC current gain | hFE(1) | 100 |  | 320 |  | VCE=2V,IC=0.05A | 1 |
| DC current gain | hFE(2) | 30 |  |  |  | VCE=2V,IC=1A | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 0.5 | V | IC=500mA,IB=50mA | 1 |
| Base-emitter saturation voltage | VBE(sat) |  |  | 1.2 | V | IC=500mA,IB=50mA | 1 |
| Transition frequency | fT | 150 |  |  | MHz | VCE=10V,IC=50mA | 1 |
| Collector output capacitance | Cob |  |  | 12 | pF | VCB=10V,IE=0,f=1MHz | 1 |

## CAD (KiCad official)

- Symbol: `KTC4378`
- Footprint: `Package_TO_SOT_SMD:SOT-89-3`
- 3D model: SOT-89-3L (KiCad packages3D, STEP)
- 3D model files: `ktc4378-etched.step` / `ktc4378-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ktc4378.step` / `ktc4378.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Changjiang Electronics Tech (CJ) datasheet](docs/ktc4378-datasheet.pdf) (1 pp, sha256 `2cfeebc5a9532a6b`, retrieved 2026-10-27, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-haiku-5-5` (text), consensus `off` (skipped (clean text read)), 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/ktc4378-datasheet.pdf)