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Contents

README

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BUL128D-B

STMicroelectronics · Bipolar (BJT) · TO-220

BUL128D-B from STMicroelectronics, in a TO-220. 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; absolute maximum base current is 2 A (4 A peak, tp < 5 ms).
2 C passive Collector with integrated antiparallel collector-emitter diode; VCES 700 V, VCEO 400 V, IC 4 A (8 A peak, tp < 5 ms).
3 E passive Emitter of the NPN transistor; the antiparallel diode is connected between emitter and collector, and V(BR)EBO is 9 V min to 18 V max at IE = 10 mA.

Key specifications

Parameter Value
Manufacturer STMicroelectronics
Package TO-220
Category Transistors/Thyristors
Pins 3

CAD (KiCad official)

  • Symbol: BUL128D-B
  • Footprint: Package_TO_SOT_THT:TO-220-3_Vertical
  • 3D model: TO-220 (KiCad packages3D, STEP)
  • 3D model files: bul128d-b-etched.step / bul128d-b-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); bul128d-b.step / bul128d-b.glb are the bare package body.

Provenance

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

  • Datasheet: STMicroelectronics datasheet (8 pp, sha256 0f91b4f2f3241156, retrieved 2026-10-05, 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