FS431M

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  "type": "component",
  "slug": "fs431m",
  "title": "FS431M",
  "brief": "FOSAN Voltage Reference, SOT-23. Pinout extracted from the datasheet, KiCad symbol/footprint/3D.",
  "version": "0.2.0",
  "license": "CC-BY-SA-4.0",
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    "pmic",
    "fs431m"
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  "component": {
    "mpn": "FS431M",
    "manufacturer": "FOSAN",
    "package": "SOT-23",
    "pin_count": 3,
    "category": "PMIC",
    "subcategory": "Voltage Reference",
    "datasheet": "https://wmsc.lcsc.com/wmsc/upload/file/pdf/v2/lcsc/2112031830_FOSAN-FS431M_C2926145.pdf",
    "parts": {
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      "model_3d_plain": "fs431m.glb",
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      "lbr": "fs431m.lbr"
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    "distributor_links": {
      "lcsc": "C2926145"
    },
    "pins": [
      {
        "number": "1",
        "name": "REF",
        "type": "input",
        "description": "Reference input. Compared internally against the 2.495 V bandgap reference; typically driven from an external R1/R2 divider between Cathode and Anode to program the regulation voltage. Input current ~1.8 µA typ (4 µA max)."
      },
      {
        "number": "2",
        "name": "K",
        "type": "passive",
        "description": "Cathode. Shunt regulation terminal; sinks 1-100 mA to hold VKA at the programmed voltage (up to 40 V absolute max, 36 V programmable). Dynamic impedance 0.27 Ω typ."
      },
      {
        "number": "3",
        "name": "A",
        "type": "passive",
        "description": "Anode. Common/ground return for the shunt regulator; the resistor divider low side and Vref return are referenced here."
      }
    ],
    "provenance": {
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        "pages": 4,
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      "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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      "footprint": "viewers/footprint.html"
    },
    "pin1": {
      "pad": "1",
      "at": [
        -0.9375,
        -0.95
      ],
      "corner": "top-left",
      "source": "silk-marker",
      "derived_from": "SOT-23@sha256:0d88c86c1b6d8c1a",
      "mark": "drawn"
    },
    "models_3d": [
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        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          2.5,
          3,
          1.2
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        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "dd5d1711204e1d8d26cd11490923bd84340820baa69538c385a4300ec2539bc0",
        "checked": "2026-10-07",
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  },
  "metadata": {
    "specs": {
      "Manufacturer": "FOSAN",
      "Package": "SOT-23",
      "Category": "PMIC",
      "Pins": "3"
    },
    "characteristics": {
      "version": 1,
      "source": "datasheet",
      "datasheet_sha256": "44eae1ca9d167d08",
      "rows": [
        {
          "name": "Reference Input Voltage (0.3% grade)",
          "symbol": "VREF",
          "kind": "electrical",
          "unit": "V",
          "min": 2.488,
          "typ": 2.495,
          "max": 2.502,
          "conditions": "VKA=VREF IKA=10mA",
          "source_page": 2,
          "source": "datasheet"
        },
        {
          "name": "Reference Input Voltage (0.5% grade)",
          "symbol": "VREF",
          "kind": "electrical",
          "unit": "V",
          "min": 2.483,
          "typ": 2.495,
          "max": 2.507,
          "conditions": "VKA=VREF IKA=10mA",
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        },
        {
          "name": "Reference Input Voltage (1% grade)",
          "symbol": "VREF",
          "kind": "electrical",
          "unit": "V",
          "min": 2.47,
          "typ": 2.495,
          "max": 2.52,
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        },
        {
          "name": "Deviation of reference input voltage over temperature",
          "symbol": "ΔVREF/ΔT",
          "kind": "electrical",
          "unit": "mV",
          "min": null,
          "typ": 3,
          "max": 17,
          "conditions": "VKA=VREF IKA=10mA, -20 ~ +70℃",
          "source_page": 2,
          "source": "datasheet"
        },
        {
          "name": "Ratio of change in reference input voltage to change in cathode voltage (ΔVKA=10V~VREF)",
          "symbol": "ΔVREF/ΔVKA",
          "kind": "electrical",
          "unit": "mV/V",
          "min": -0.4,
          "typ": 0,
          "max": 2.7,
          "conditions": "IKA=10mA, ΔVKA=10V~VREF",
          "source_page": 2,
          "source": "datasheet"
        },
        {
          "name": "Ratio of change in reference input voltage to change in cathode voltage (ΔVKA=36V~10V)",
          "symbol": "ΔVREF/ΔVKA",
          "kind": "electrical",
          "unit": "mV/V",
          "min": -0.4,
          "typ": 0,
          "max": 2,
          "conditions": "IKA=10mA, ΔVKA=36V~10V",
          "source_page": 2,
          "source": "datasheet"
        },
        {
          "name": "Reference input current",
          "symbol": "IREF",
          "kind": "electrical",
          "unit": "µA",
          "min": null,
          "typ": 1.8,
          "max": 4,
          "conditions": "IKA=10mA, R1=10kΩ, R2=∞",
          "source_page": 2,
          "source": "datasheet"
        },
        {
          "name": "Deviation of reference input current over full temperature range",
          "symbol": "ΔIREF/ΔT",
          "kind": "electrical",
          "unit": "µA",
          "min": null,
          "typ": 0.4,
          "max": 1.2,
          "conditions": "IKA=10mA, R1=10kΩ, R2=∞, TA=-20 ~ +85℃",
          "source_page": 2,
          "source": "datasheet"
        },
        {
          "name": "Minimum cathode current for regulation",
          "symbol": "IKA(MIN)",
          "kind": "electrical",
          "unit": "mA",
          "min": null,
          "typ": 0.25,
          "max": 0.5,
          "conditions": "VKA=VREF",
          "source_page": 2,
          "source": "datasheet"
        },
        {
          "name": "Off-state cathode current",
          "symbol": "IKA(OFF)",
          "kind": "electrical",
          "unit": "µA",
          "min": null,
          "typ": 0.17,
          "max": 1,
          "conditions": "VKA=40V, VREF=0V",
          "source_page": 2,
          "source": "datasheet"
        },
        {
          "name": "Dynamic impedance",
          "symbol": "ZKA",
          "kind": "electrical",
          "unit": "Ω",
          "min": null,
          "typ": 0.27,
          "max": 0.5,
          "conditions": "VKA=VREF, IKA=1 ~ 100mA, f≤1kHz",
          "source_page": 2,
          "source": "datasheet"
        },
        {
          "name": "Cathode to anode voltage",
          "symbol": "VKA",
          "kind": "absolute_maximum",
          "unit": "V",
          "min": null,
          "typ": null,
          "max": 40,
          "conditions": "",
          "source_page": 1,
          "source": "datasheet"
        },
        {
          "name": "Cathode current range",
          "symbol": "IK",
          "kind": "absolute_maximum",
          "unit": "mA",
          "min": -100,
          "typ": null,
          "max": 150,
          "conditions": "",
          "source_page": 1,
          "source": "datasheet"
        },
        {
          "name": "Reference input current range",
          "symbol": "IREF",
          "kind": "absolute_maximum",
          "unit": "mA",
          "min": -0.05,
          "typ": null,
          "max": 10,
          "conditions": "",
          "source_page": 1,
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        },
        {
          "name": "Power dissipation",
          "symbol": "PD",
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          "unit": "mW",
          "min": null,
          "typ": null,
          "max": 200,
          "conditions": "",
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        },
        {
          "name": "Thermal resistance junction-ambient",
          "symbol": "RΘJA",
          "kind": "thermal",
          "unit": "℃/W",
          "min": null,
          "typ": null,
          "max": 625,
          "conditions": "",
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        },
        {
          "name": "Junction and storage temperature",
          "symbol": "TJ,Tstg",
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          "unit": "℃",
          "min": -40,
          "typ": null,
          "max": 125,
          "conditions": "",
          "source_page": 1,
          "source": "datasheet"
        },
        {
          "name": "Operating ambient temperature",
          "symbol": "Top",
          "kind": "recommended_operating",
          "unit": "℃",
          "min": -20,
          "typ": null,
          "max": 70,
          "conditions": "",
          "source_page": 1,
          "source": "datasheet"
        }
      ]
    }
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  "discovery_pitch": "FS431M (FOSAN) component page with datasheet-verified CAD.",
  "author": {
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  "updated_at": "2026-09-24T20:46:59.837Z"
}