# BU931P

**STMicroelectronics** · Darlington Transistors · TO-247-3

BU931P from STMicroelectronics, in a TO-247-3. 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 | B | input | Base of the NPN Darlington; absolute maximum IB 1 A (IBM 5 A peak) and VEBO 5 V. |
| 2 | C | passive | Collector, also connected to the TAB; VCEO 400 V, VCES 500 V, IC 15 A (ICM 30 A peak). |
| 3 | E | passive | Emitter of the Darlington, with the internal collector-emitter diode connected across C and E. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | STMicroelectronics |
| Package | TO-247-3 |
| Category | Transistors/Thyristors |
| Pins | 3 |

## CAD (KiCad official)

- Symbol: `BU931P`
- Footprint: `Package_TO_SOT_THT:TO-247-3_Vertical`
- 3D model: TO-247-3 (KiCad packages3D, STEP)
- 3D model files: `bu931p-etched.step` / `bu931p-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bu931p.step` / `bu931p.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [STMicroelectronics datasheet](https://www.st.com/resource/en/datasheet/bu931p.pdf) (11 pp, sha256 `d944d69c618e8ecb`, retrieved 2026-10-05, tier: manufacturer)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-haiku-4-5-20251001` (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/bu931p-datasheet.pdf)