# BD140

**STMicroelectronics** · Bipolar Transistor (BJT) · TO-126

The BD140 is a PNP medium-power transistor rated for 80 V and 1.5 A continuous collector current in a TO-126 package. It is the complement of the NPN BD139, and the two are paired in class-AB audio output stages, complementary drivers, and general medium-power switching.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | E | passive | Emitter of the PNP BJT. Typical VCE(sat) = -0.5 V at IC = -0.5 A, IB = -0.05 A; VBE approximately -1 V at IC = -0.5 A, VCE = -2 V. |
| 2 | C | passive | Collector of the PNP BJT. Also electrically bonded to the metal mounting tab of the SOT-32/TO-126 package. Absolute maximum VCEO = -80 V, VCBO = -80 V, IC = -1.5 A continuous, ICM = -3 A peak. |
| 3 | B | input | Base of the PNP BJT. Drives collector current via hFE (typ. 40..250 at IC = -150 mA, VCE = -2 V). Absolute maximum VEBO = -5 V, IB = -0.5 A. |

## Key specifications

| Parameter | Value |
|---|---|
| Type | PNP medium-power transistor |
| Collector-emitter voltage (VCEO) | -80 V |
| Collector current (IC) | -1.5 A continuous (-3 A peak) |
| DC current gain (hFE) | 40 to 250 |
| Transition frequency (fT) | 75 MHz |
| Power dissipation | 12.5 W |
| Operating temperature | -55 C to 150 C |

## Ordering variants

- `BD140`
- `BD140-10`
- `BD140-16`

## 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 (IE = 0) | VCBO |  |  | -80 | V | IE = 0 | 3 |
| Collector-emitter voltage (IB = 0) | VCEO |  |  | -80 | V | IB = 0 | 3 |
| Emitter-base voltage (IC = 0) | VEBO |  |  | -5 | V | IC = 0 | 3 |
| Collector current | IC |  |  | -1.5 | A |  | 3 |
| Collector peak current | ICM |  |  | -3 | A |  | 3 |
| Base current | IB |  |  | -0.5 | A |  | 3 |
| Total dissipation at Tc ≤ 25 °C | PTOT |  |  | 12.5 | W | Tc ≤ 25 °C | 3 |
| Total dissipation at Tamb ≤ 25 °C | PTOT |  |  | 1.25 | W | Tamb ≤ 25 °C | 3 |
| Storage temperature | Tstg | -65 |  | 150 | °C |  | 3 |
| Max. operating junction temperature | Tj |  |  | 150 | °C |  | 3 |
| 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) | VCEO(sus) | -80 |  |  | V | IC = -30 mA, BD140 | 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 |
| Thermal resistance junction-case | Rthj-case |  |  | 10 | °C/W |  | 3 |
| Thermal resistance junction-ambient | Rthj-amb |  |  | 100 | °C/W |  | 3 |

## CAD (KiCad official)

- Symbol: `bd140.kicad_sym`
- Footprint: `bd140.kicad_mod`
- 3D model: TO-126 body from KiCad `Package_TO_SOT_THT/TO-126-3_Vertical`.
- 3D model files: `bd140-etched.step` / `bd140-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bd140.step` / `bd140.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/bd140.pdf) (9 pp, sha256 `9a72cdfa334700b8`, retrieved 2026-08-17, tier: manufacturer)
- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/bd140-datasheet.pdf)