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BD137 NPN Power Transistor
Public Unreviewedby Ray
NPN medium-power transistor, 60 V / 1.5 A, in TO-126 for audio and driver stages.
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markdownBD137
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
BD137BD137-10BD137-16
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 (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).