BD137 NPN Power Transistor

@@ -0,0 +1,47 @@+# BD137++**STMicroelectronics** · Bipolar Transistor (BJT) · TO-126++The BD137 is an NPN medium-power transistor rated for 60 V and 1.5 A continuous collector current in a TO-126 package. It sits between the BD135 (45 V) and BD139 (80 V) in the series, and is used in audio driver and output stages, discrete regulators, and medium-power switching.++## Pinout++| Pin | Name | Type | Function |+|---|---|---|---|+| 1 | E | passive | Emitter. Typically the low-side reference of the transistor; VCE(sat) ≤ 0.5 V at IC = 0.5 A, IB = 50 mA. |+| 2 | C | passive | Collector. Also thermally/electrically tied to the metal mounting tab of the SOT-32 (TO-126) package. Rated IC = 1.5 A continuous, ICM = 3 A peak; VCEO ≈ 60 V for BD137. |+| 3 | B | input | Base. Controls collector current via base drive; VBE ≈ 1 V at IC = 0.5 A. Absolute max IB = 0.5 A, VEBO = 5 V. |++## Key specifications++| Parameter | Value |+|---|---|+| Type | NPN medium-power transistor |+| Collector-emitter voltage (VCEO) | 60 V |+| Collector current (IC) | 1.5 A continuous (3 A peak) |+| DC current gain (hFE) | 40 to 250 |+| Transition frequency (fT) | 190 MHz |+| Power dissipation | 12.5 W |+| Operating temperature | -55 C to 150 C |++## Ordering variants++- `BD137`+- `BD137-10`+- `BD137-16`++## CAD (KiCad official)++- Symbol: `bd137.kicad_sym`+- Footprint: `bd137.kicad_mod`+- 3D model: TO-126 body from KiCad `Package_TO_SOT_THT/TO-126-3_Vertical`.++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [STMicroelectronics datasheet](https://www.st.com/resource/en/datasheet/bd135.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/bd137-datasheet.pdf)

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