BD139 NPN Power Transistor

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  "slug": "bd139",
  "title": "BD139 NPN Power Transistor",
  "brief": "NPN medium-power transistor, 80 V / 1.5 A, in a TO-126 package for audio and driver stages.",
  "version": "0.1.0",
  "license": "CC-BY-SA-4.0",
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    "bjt",
    "npn",
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    "st"
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  "component": {
    "mpn": "BD139",
    "manufacturer": "STMicroelectronics",
    "package": "TO-126",
    "pin_count": 3,
    "category": "Discrete Semiconductor",
    "subcategory": "Bipolar Transistor (BJT)",
    "datasheet": "https://www.st.com/resource/en/datasheet/bd139.pdf",
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    "distributor_links": {},
    "pins": [
      {
        "number": "1",
        "name": "E",
        "type": "passive",
        "description": "Emitter terminal of the NPN BJT. Absolute maximum VEBO = 5 V. Typically returned to ground or a low-impedance node in common-emitter audio driver stages."
      },
      {
        "number": "2",
        "name": "C",
        "type": "passive",
        "description": "Collector terminal of the NPN BJT. Absolute maximum VCEO = 80 V, VCBO = 80 V. Continuous IC = 1.5 A, peak ICM = 3 A. VCE(sat) ≤ 0.5 V at IC = 0.5 A, IB = 0.05 A. Collector tab is electrically common to the metal mounting tab of the SOT-32 package."
      },
      {
        "number": "3",
        "name": "B",
        "type": "input",
        "description": "Base terminal of the NPN BJT. Absolute maximum base current IB = 0.5 A. Typical VBE ≈ 1 V at IC = 0.5 A, VCE = 2 V. Drives collector current via hFE (40-250 at IC = 150 mA)."
      }
    ],
    "provenance": {
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      "datasheet": {
        "url": "https://www.st.com/resource/en/datasheet/bd139.pdf",
        "pages": 9,
        "sha256": "9a72cdfa334700b8",
        "source_tier": "mfr"
      },
      "cad": "KiCad official (CC-BY-SA 4.0)",
      "pins": {
        "total": 3,
        "described": 3,
        "cites_pages": true,
        "refuses_to_fabricate": true
      }
    },
    "viewers": {
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        "role": "plain",
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        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "body on z = 0, through-hole leads below",
        "extents_mm": [
          8.0,
          3.25,
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        ],
        "zmin_mm": -9.75,
        "centre_offset_mm": 0.375,
        "footprint_binding": "identity",
        "sha256": "6cb4ab2049af821a4bd7162ee7b11b91bdea76f43915d9c1fbb0cb1cdeeaa9c6",
        "checked": "2026-10-07",
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        "checked": "2026-10-07",
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    ]
  },
  "metadata": {
    "specs": {
      "Type": "NPN 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)": "190 MHz",
      "Power dissipation": "12.5 W",
      "Operating temperature": "-55 C to 150 C"
    },
    "characteristics": {
      "version": 1,
      "source": "datasheet",
      "datasheet_sha256": "9a72cdfa334700b8",
      "rows": [
        {
          "name": "Collector-emitter sustaining voltage (IB=0), BD139",
          "symbol": "VCEO(sus)",
          "kind": "electrical",
          "unit": "V",
          "min": 80,
          "typ": null,
          "max": null,
          "conditions": "IC = 30 mA (pulsed, 300 µs, duty cycle 1.5%)",
          "source_page": 4,
          "source": "datasheet"
        },
        {
          "name": "Collector cut-off current (IE=0), NPN",
          "symbol": "ICBO",
          "kind": "electrical",
          "unit": "µA",
          "min": null,
          "typ": null,
          "max": 0.1,
          "conditions": "VCB = 30 V",
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        {
          "name": "Collector cut-off current (IE=0), NPN, hot",
          "symbol": "ICBO",
          "kind": "electrical",
          "unit": "µA",
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          "max": 10,
          "conditions": "VCB = 30 V, TC = 125 °C",
          "source_page": 4,
          "source": "datasheet"
        },
        {
          "name": "Emitter cut-off current (IC=0), NPN",
          "symbol": "IEBO",
          "kind": "electrical",
          "unit": "µA",
          "min": null,
          "typ": null,
          "max": 10,
          "conditions": "VEB = 5 V",
          "source_page": 4,
          "source": "datasheet"
        },
        {
          "name": "Collector-emitter saturation voltage, NPN",
          "symbol": "VCE(sat)",
          "kind": "electrical",
          "unit": "V",
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          "typ": null,
          "max": 0.5,
          "conditions": "IC = 0.5 A, IB = 0.05 A",
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        {
          "name": "Base-emitter voltage, NPN",
          "symbol": "VBE",
          "kind": "electrical",
          "unit": "V",
          "min": null,
          "typ": null,
          "max": 1,
          "conditions": "IC = 0.5 A, VCE = 2 V",
          "source_page": 4,
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        },
        {
          "name": "DC current gain, NPN",
          "symbol": "hFE",
          "kind": "electrical",
          "unit": "",
          "min": 25,
          "typ": null,
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          "conditions": "IC = 5 mA, VCE = 2 V",
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        },
        {
          "name": "DC current gain, NPN",
          "symbol": "hFE",
          "kind": "electrical",
          "unit": "",
          "min": 40,
          "typ": null,
          "max": null,
          "conditions": "IC = 150 mA, VCE = 2 V",
          "source_page": 4,
          "source": "datasheet"
        },
        {
          "name": "DC current gain, NPN (max for the three printed conditions)",
          "symbol": "hFE",
          "kind": "electrical",
          "unit": "",
          "min": null,
          "typ": null,
          "max": 250,
          "conditions": "IC = 5 mA, VCE = 2 V; IC = 150 mA, VCE = 2 V; IC = 0.5 A, VCE = 2 V",
          "source_page": 4,
          "source": "datasheet"
        },
        {
          "name": "Collector-base voltage (IE = 0), BD139",
          "symbol": "VCBO",
          "kind": "absolute_maximum",
          "unit": "V",
          "min": null,
          "typ": null,
          "max": 80,
          "conditions": "IE = 0",
          "source_page": 3,
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        },
        {
          "name": "Collector-emitter voltage (IB = 0), BD139",
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          "conditions": "IB = 0",
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        },
        {
          "name": "Emitter-base voltage (IC = 0)",
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          "unit": "V",
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          "typ": null,
          "max": 5,
          "conditions": "IC = 0",
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        },
        {
          "name": "Collector current",
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          "unit": "A",
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        },
        {
          "name": "Collector peak current",
          "symbol": "ICM",
          "kind": "absolute_maximum",
          "unit": "A",
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          "typ": null,
          "max": 3,
          "conditions": "",
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        },
        {
          "name": "Base current",
          "symbol": "IB",
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          "unit": "A",
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          "max": 0.5,
          "conditions": "",
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        },
        {
          "name": "Total dissipation",
          "symbol": "PTOT",
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          "unit": "W",
          "min": null,
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          "conditions": "Tc ≤ 25 °C",
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        {
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          "min": null,
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          "max": 1.25,
          "conditions": "Tamb ≤ 25 °C",
          "source_page": 3,
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        {
          "name": "Max. operating junction temperature",
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          "name": "Thermal resistance junction-case",
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  "discovery_triggers": [
    "medium-power NPN",
    "audio driver transistor",
    "1.5A transistor",
    "class-AB output"
  ],
  "discovery_pitch": "An 80 V, 1.5 A NPN for audio output stages, linear regulators, and general medium-power switching, paired with the BD140 PNP.",
  "author": {
    "name": "Ray",
    "email": "[email protected]"
  },
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