TL431

{
  "schema_version": 1,
  "type": "component",
  "slug": "tl431",
  "title": "TL431",
  "brief": "TI adjustable precision shunt regulator, SOT-23. Vref 2.5 V, programmable to 36 V, sinks 1-100 mA. Datasheet-verified.",
  "version": "0.1.1",
  "license": "CC-BY-SA-4.0",
  "tags": [
    "component",
    "voltage-reference",
    "shunt-regulator",
    "tl431",
    "sot-23",
    "texas-instruments"
  ],
  "component": {
    "mpn": "TL431",
    "manufacturer": "Texas Instruments",
    "package": "SOT-23 (DBZ)",
    "pin_count": 3,
    "category": "Power Management",
    "subcategory": "Adjustable shunt voltage reference",
    "datasheet": "https://www.ti.com/lit/ds/symlink/tl431.pdf",
    "parts": {
      "symbol": "tl431.kicad_sym",
      "footprint": "tl431.kicad_mod",
      "model_3d": "tl431-etched.glb",
      "model_3d_plain": "tl431.glb",
      "lbr": "tl431.lbr",
      "model_3d_step": "tl431-etched.step",
      "model_3d_step_plain": "tl431.step"
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    "distributor_links": {},
    "pins": [
      {
        "number": "1",
        "name": "K",
        "type": "passive",
        "description": "Shunt cathode (K). Current-sink terminal referenced to ANODE; V(KA) may range from Vref (~2.5 V) up to the absolute-max 37 V. Continuous cathode current I(KA) = 1 mA to 100 mA in normal operation (abs-max −100 to 150 mA). Sinks current when V(REF-ANODE) exceeds Vref, regulating V(KA) at the value set by the external divider."
      },
      {
        "number": "2",
        "name": "REF",
        "type": "input",
        "description": "Reference (feedback) input, threshold relative to ANODE. Internal error amp regulates V(REF) to Vref (~2.5 V nominal, 0.5%/1%/2% grades). Reference input current I(ref) is very small (abs-max −0.05 to 10 mA); typically driven from a resistor divider between CATHODE and ANODE to program V(KA) = Vref × (1 + R1/R2) + I(ref)·R1."
      },
      {
        "number": "3",
        "name": "A",
        "type": "passive",
        "description": "Common return terminal (A), normally connected to circuit ground. All device voltages (V(KA), V(REF)) are referenced to ANODE. Carries the sum of cathode sink current and reference-input current."
      }
    ],
    "provenance": {
      "extractor": "ds2sf",
      "datasheet": {
        "url": "https://www.ti.com/lit/ds/symlink/tl431.pdf",
        "pages": 85,
        "sha256": "49d4bc6e1bdcfab7",
        "source_tier": "mfr"
      },
      "cad": "KiCad official (CC-BY-SA 4.0)",
      "pins": {
        "total": 3,
        "described": 3,
        "cites_pages": true,
        "refuses_to_fabricate": true
      }
    },
    "viewers": {
      "symbol": "viewers/symbol.html",
      "footprint": "viewers/footprint.html"
    },
    "models_3d": [
      {
        "file": "tl431.step",
        "role": "plain",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          2.5,
          3,
          1.2
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "dd5d1711204e1d8d26cd11490923bd84340820baa69538c385a4300ec2539bc0",
        "checked": "2026-11-10",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      },
      {
        "file": "tl431-etched.step",
        "role": "plain",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
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        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "02578c3839b8140ccb0b1104d051d111b068de7d3820be3fb92a86327e450118",
        "checked": "2026-11-10",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      }
    ]
  },
  "metadata": {
    "specs": {
      "Type": "Adjustable shunt voltage reference",
      "Reference voltage (Vref)": "2.5 V (typ 2.495 V)",
      "Output range": "Vref to 36 V (external divider)",
      "Cathode current": "1 mA to 100 mA",
      "Output impedance": "0.2 Ω typ",
      "Package": "SOT-23 (DBZ)",
      "Body (L×W×H)": "2.9 × 1.3 × 1.1 mm"
    }
  },
  "discovery_triggers": [
    "tl431",
    "shunt voltage reference",
    "adjustable zener",
    "supply feedback reference"
  ],
  "discovery_pitch": "TL431 adjustable precision shunt regulator (SOT-23) with datasheet-verified pinout, KiCad symbol/footprint/3D, and full provenance.",
  "author": {
    "name": "Ray"
  },
  "dependencies": {},
  "hero": {
    "type": "image",
    "path": "docs/hero.png"
  },
  "files": [
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    "README.md",
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    "tl431.kicad_mod",
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    "tl431.lbr",
    "docs/hero.png",
    "docs/tl431-datasheet.pdf",
    "viewers/symbol.html",
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  "variants": [
    {
      "mpn": "TL431AIDBZR (SOT-23, ±0.5%)",
      "kind": "packaging"
    },
    {
      "mpn": "TL431BIDBZR (SOT-23, ±0.5%, tighter tempco)",
      "kind": "packaging"
    }
  ],
  "description": "TI adjustable precision shunt regulator, SOT-23. Vref 2.5 V, programmable to 36 V, sinks 1-100 mA. Datasheet-verified.",
  "org": "adom"
}