# BU508AW

**STMicroelectronics** · Bipolar (BJT) · TO-247

BU508AW from STMicroelectronics, in a TO-247. 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 transistor; base current IB is rated to 4 A maximum and VEBO to 9 V. |
| 2 | C | passive | Collector of the NPN transistor; VCES is 1500 V, VCEO is 700 V, and IC is 8 A continuous (15 A peak, tP < 5 ms). |
| 3 | E | passive | Emitter of the NPN transistor, the common return for the base drive and collector current. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | STMicroelectronics |
| Package | TO-247 |
| 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-emitter voltage (VBE = 0) | VCES |  |  | 1500 | V | VBE = 0 | 3 |
| Collector-emitter voltage (IB = 0) | VCEO |  |  | 700 | V | IB = 0 | 3 |
| Collector-base voltage (IC = 0) | VEBO |  |  | 9 | V | IC = 0 | 3 |
| Collector current | IC |  |  | 8 | A |  | 3 |
| Collector peak current | ICM |  |  | 15 | A | tP < 5ms | 3 |
| Base current | IB |  |  | 4 | A |  | 3 |
| Total dissipation | PTOT |  |  | 125 | W | Tc = 25°C | 3 |
| Storage temperature | Tstg | -65 |  | 150 | °C |  | 3 |
| Max. operating junction temperature | TJ |  |  | 150 | °C |  | 3 |
| Thermal resistance junction-case | Rthj-case |  |  | 1 | °C/W |  | 3 |
| Collector cut-off current (VBE = 0) | ICES |  |  | 0.2 | mA | VCE = 1500V | 4 |
| Collector cut-off current (VBE = 0) | ICES |  |  | 2 | mA | VCE = 1500V; TC = 125°C | 4 |
| Emitter cut-off current (IC = 0) | IEBO |  |  | 1 | mA | VEB = 9V | 4 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 1 | V | IC = 4.5A IB = 1.6A; pulsed: pulse duration = 300 ms, duty cycle 1.5 % | 4 |
| Base-emitter saturation voltage | VBE(sat) |  |  | 1.1 | V | IC = 4.5A IB = 2A | 4 |
| DC current gain | hFE | 10 |  |  |  | IC = 0.1A VCE = 5V | 4 |
| DC current gain | hFE | 5 |  | 30 |  | IC = 4.5A VCE = 5V | 4 |

## CAD (KiCad official)

- Symbol: `BU508AW`
- Footprint: `Package_TO_SOT_THT:TO-247-3_Vertical`
- 3D model: TO-247 (KiCad packages3D, STEP)
- 3D model files: `bu508aw-etched.step` / `bu508aw-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bu508aw.step` / `bu508aw.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [STMicroelectronics datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8588894837777448960) (11 pp, sha256 `74d16a9ca70e669f`, retrieved 2026-11-12, 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/bu508aw-datasheet.pdf)