# BD135-16

**STMicroelectronics** · Bipolar Transistors - BJT · TO-126

BD135-16 from STMicroelectronics, in a TO-126. 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; the datasheet lists a maximum base current of 0.5 A and a maximum emitter-base voltage of 5 V. |
| 2 | C | passive | Collector (also connected to the mounting tab); the BD135 is rated for VCEO of 45 V and a collector current of 1.5 A (3 A peak). |
| 3 | E | passive | Emitter of the NPN transistor, which carries the 1.5 A maximum collector current. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | STMicroelectronics |
| Package | TO-126 |
| Category | Triode/MOS Tube/Transistor |
| 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 cut-off current (IE=0) | ICBO |  |  | 0.1 | µA | VCB = 30 V | 4 |
| Collector cut-off current (IE=0) | ICBO |  |  | 10 | µA | VCB = 30 V, TC = 125 °C | 4 |
| Emitter cut-off current (IC=0) | IEBO |  |  | 10 | µA | VEB = 5 V | 4 |
| Collector-emitter sustaining voltage (IB=0), BD135 | VCEO(sus) | 45 |  |  | V | IC = 30 mA | 4 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 0.5 | V | IC = 0.5 A, IB = 0.05 A | 4 |
| Base-emitter voltage | VBE |  |  | 1 | V | IC = 0.5 A, VCE = 2 V | 4 |
| DC current gain | hFE | 25 |  |  |  | IC = 5 mA, VCE = 2 V | 4 |
| DC current gain | hFE | 40 |  | 250 |  | IC = 150 mA, VCE = 2 V | 4 |
| DC current gain hFE group 16 (BD135-16) | hFE | 100 |  | 250 |  | IC = 150 mA, VCE = 2 V | 4 |
| Collector-emitter voltage (IB = 0) | VCEO |  |  | 45 | V |  | 3 |
| Collector-base voltage (IE = 0) | VCBO |  |  | 45 | V |  | 3 |
| Emitter-base voltage (IC = 0) | VEBO |  |  | 5 | V |  | 3 |
| Collector current | IC |  |  | 1.5 | A |  | 3 |
| Collector peak current | ICM |  |  | 3 | A |  | 3 |
| Base current | IB |  |  | 0.5 | A |  | 3 |
| Total dissipation | PTOT |  |  | 12.5 | W | Tc ≤ 25 °C | 3 |
| Total dissipation | PTOT |  |  | 1.25 | W | Tamb ≤ 25 °C | 3 |
| Storage temperature | Tstg | -65 |  | 150 | °C |  | 3 |
| Max. operating junction temperature | Tj |  |  | 150 | °C |  | 3 |
| Thermal resistance junction-case | Rthj-case |  |  | 10 | °C/W |  | 3 |
| Thermal resistance junction-ambient | Rthj-amb |  |  | 100 | °C/W |  | 3 |

## CAD (KiCad official)

- Symbol: `BD135-16`
- Footprint: `Package_TO_SOT_THT:TO-126-3_Vertical`
- 3D model: TO-126 (KiCad packages3D, STEP)
- 3D model files: `bd135-16-etched.step` / `bd135-16-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bd135-16.step` / `bd135-16.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/bd135-16.pdf) (9 pp, sha256 `9a72cdfa334700b8`, retrieved 2026-11-07, tier: manufacturer)
- **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/bd135-16-datasheet.pdf)