# 2SC4738

**Changjing** · Bipolar (BJT) · SOT-523

2SC4738 from Changjing, in a SOT-523. 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 gives emitter-base breakdown V(BR)EBO of 5 V minimum at IE=100µA and a VEBO rating of 5 V. |
| 2 | EMITTER | passive | Emitter terminal of the NPN transistor; the datasheet gives an emitter-base voltage rating VEBO of 5 V and an emitter cut-off current IEBO of 100 nA max at VEB=5V. |
| 3 | COLLECTOR | passive | Collector terminal of the NPN transistor; the datasheet rates it for VCBO 60 V, VCEO 50 V, IC 150 mA continuous collector current and PC 100 mW collector power dissipation. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Changjing |
| Package | SOT-523 |
| 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=100µA, 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=100µA, IC=0 | 1 |
| Collector cut-off current | ICBO |  |  | 100 | nA | VCB=60V, IE=0 | 1 |
| Emitter cut-off current | IEBO |  |  | 100 | nA | VEB=5V, IC=0 | 1 |
| DC current gain | hFE | 120 |  | 700 |  | VCE=6V, IC=2mA | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 0.25 | V | IC=100mA, IB=10mA | 1 |
| Transition frequency | fT | 80 |  |  | MHz | VCE=10V, IC=1mA | 1 |
| Collector output capacitance | Cob |  |  | 3.5 | pF | VCB=10V, IE=0, f=1MHz | 1 |
| Collector-base voltage | VCBO |  |  | 60 | V |  | 1 |
| Collector-emitter voltage | VCEO |  |  | 50 | V |  | 1 |
| Emitter-base voltage | VEBO |  |  | 5 | V |  | 1 |
| Collector current | IC |  |  | 150 | mA |  | 1 |
| Collector power dissipation | PC |  |  | 100 | mW |  | 1 |
| Operation junction and storage temperature range | TJ,Tstg | -55 |  | 150 | ℃ |  | 1 |
| Thermal resistance from junction to ambient | RΘJA |  |  | 1250 | ℃/W |  | 1 |

## CAD (KiCad official)

- Symbol: `2SC4738`
- Footprint: `Package_TO_SOT_SMD:SOT-523`
- 3D model: SOT-523, generated from the KiCad footprint (body from the F.Fab outline, terminals on the pads, 0.8 mm nominal SOT-523 height). Neither the vendor nor KiCad ships a 3D model for this package, so the dimensions are nominal, not the manufacturer's CAD (STEP)
- 3D model files: `2sc4738-etched.step` / `2sc4738-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `2sc4738.step` / `2sc4738.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Changjing datasheet](docs/2sc4738-datasheet.pdf) (4 pp, sha256 `907cad450afd7431`, 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/2sc4738-datasheet.pdf)