# 2SD1781KT146R

**ROHM Semicon** · Bipolar (BJT) · TO-236-3(SOT-23-3)

2SD1781KT146R from ROHM Semicon, in a TO-236-3(SOT-23-3). 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 | E | passive | Emitter terminal of the NPN transistor, with VEBO rated 5 V maximum. |
| 2 | B | passive | Base terminal of the NPN transistor, driven with IB=50mA for IC=500mA at VCE(sat) of 0.1V typ. |
| 3 | C | passive | Collector terminal of the NPN transistor, rated VCEO 32 V, VCBO 40 V and IC 800 mA continuous (1.5 A pulsed). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | ROHM Semicon |
| Package | TO-236-3(SOT-23-3) |
| 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 |  |  | 40 | V |  | 2 |
| Collector-emitter voltage | VCEO |  |  | 32 | V |  | 2 |
| Emitter-base voltage | VEBO |  |  | 5 | V |  | 2 |
| Collector current | IC |  |  | 800 | mA |  | 2 |
| Collector current (pulse) | ICP |  |  | 1.5 | A | Pw=100ms Single pulse | 2 |
| Power dissipation | PD |  |  | 200 | mW | Each terminal mounted on a reference land | 2 |
| Junction temperature | Tj |  |  | 150 | ℃ |  | 2 |
| Range of storage temperature | Tstg | -55 |  | 150 | ℃ |  | 2 |
| Collector-base breakdown voltage | BVCBO | 40 |  |  | V | IC = 50μA | 2 |
| Collector-emitter breakdown voltage | BVCEO | 32 |  |  | V | IC = 1mA | 2 |
| Emitter-base breakdown voltage | BVEBO | 5 |  |  | V | IE = 50μA | 2 |
| Collector cut-off current | ICBO |  |  | 500 | nA | VCB = 20V | 2 |
| Emitter cut-off current | IEBO |  |  | 500 | nA | VEB = 4V | 2 |
| Collector-emitter saturation voltage | VCE(sat) |  | 100 | 400 | mV | IC = 500mA, IB = 50mA | 2 |
| DC current gain | hFE | 120 |  | 390 | - | VCE = 3V, IC = 100mA | 2 |

## CAD (KiCad official)

- Symbol: `2SD1781KT146R`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: TO-236-3(SOT-23-3) (KiCad packages3D, STEP)
- 3D model files: `2sd1781kt146r-etched.step` / `2sd1781kt146r-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `2sd1781kt146r.step` / `2sd1781kt146r.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [ROHM Semicon datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8586202609200082944) (8 pp, sha256 `abe3769562c69ce5`, retrieved 2026-10-13, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-5-5` (text+vision), consensus `claude-opus-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/2sd1781kt146r-datasheet.pdf)