74HC251D

{
  "slug": "74hc251d",
  "version": "0.1.0",
  "type": "component",
  "description": "Nexperia Signal Switches, Multiplexers, Decoders, SOIC-16. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.",
  "tags": [
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    "logic",
    "74hc251d",
    "factory-2.0.0",
    "extractor-text"
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  "dependencies": {},
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    "viewers/footprint.html",
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  "component": {
    "mpn": "74HC251D",
    "manufacturer": "Nexperia",
    "package": "SOIC-16",
    "pin_count": 16,
    "category": "Logic",
    "subcategory": "Signal Switches, Multiplexers, Decoders",
    "datasheet": "https://assets.nexperia.com/documents/data-sheet/74HC251D.pdf",
    "parts": {
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      "footprint": "74hc251d.kicad_mod",
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      "lbr": "74hc251d.lbr"
    },
    "distributor_links": {
      "lcsc": "C148202",
      "mouser": "771-74HC251D"
    },
    "distributor_check": {
      "checked_at": "2026-10-18T05:01:01Z",
      "source": "Component Ocean /api/assign-pns",
      "digikey": {
        "pn": null,
        "status": "no match"
      },
      "mouser": {
        "pn": "771-74HC251D",
        "status": "found",
        "lifecycle": "End of Life"
      }
    },
    "pins": [
      {
        "number": "1",
        "name": "I3",
        "type": "input",
        "description": "Data input I3 of the 8-input multiplexer, selected when S2 is LOW and S1 and S0 are HIGH with OE LOW; the datasheet gives the input range as 0 V to VCC and states the clamp diodes allow current-limited interfacing to voltages above VCC."
      },
      {
        "number": "2",
        "name": "I2",
        "type": "input",
        "description": "Data input I2 of the 8-input multiplexer, selected when S2 is LOW, S1 is HIGH and S0 is LOW with OE LOW; the input range is 0 V to VCC and clamp diodes allow current-limited interfacing to voltages above VCC."
      },
      {
        "number": "3",
        "name": "I1",
        "type": "input",
        "description": "Data input I1 of the 8-input multiplexer, selected when S2 is LOW, S1 is LOW and S0 is HIGH with OE LOW; the input range is 0 V to VCC and clamp diodes allow current-limited interfacing to voltages above VCC."
      },
      {
        "number": "4",
        "name": "I0",
        "type": "input",
        "description": "Data input I0 of the 8-input multiplexer, selected when S2, S1 and S0 are all LOW with OE LOW; the input range is 0 V to VCC and clamp diodes allow current-limited interfacing to voltages above VCC."
      },
      {
        "number": "5",
        "name": "Y",
        "type": "output",
        "description": "Multiplexer output that follows the selected data input (non-inverting) and goes to the high-impedance OFF-state when OE is HIGH, per the function table."
      },
      {
        "number": "6",
        "name": "~{Y}",
        "type": "output",
        "description": "Complementary multiplexer output that carries the inverse of the selected data input and goes to the high-impedance OFF-state when OE is HIGH, per the function table."
      },
      {
        "number": "7",
        "name": "OE",
        "type": "input",
        "description": "Output enable input; the function table shows a HIGH level forces Y and Y̅ to high-impedance (Z) and the Section 1 text says a HIGH on OE causes the high-impedance OFF-state, although Table 2 labels it active LOW."
      },
      {
        "number": "8",
        "name": "GND",
        "type": "power_in",
        "description": "Ground pin at 0 V, the reference for all voltages stated in the datasheet."
      },
      {
        "number": "9",
        "name": "S2",
        "type": "input",
        "description": "Common data select input (most significant select bit) that, together with S1 and S0, chooses which data input I0 to I7 is routed to Y and Y̅."
      },
      {
        "number": "10",
        "name": "S1",
        "type": "input",
        "description": "Common data select input (middle select bit) that, together with S2 and S0, chooses which data input I0 to I7 is routed to Y and Y̅."
      },
      {
        "number": "11",
        "name": "S0",
        "type": "input",
        "description": "Common data select input (least significant select bit) that, together with S2 and S1, chooses which data input I0 to I7 is routed to Y and Y̅."
      },
      {
        "number": "12",
        "name": "I7",
        "type": "input",
        "description": "Data input I7 of the 8-input multiplexer, selected when S2, S1 and S0 are all HIGH with OE LOW; the input range is 0 V to VCC and clamp diodes allow current-limited interfacing to voltages above VCC."
      },
      {
        "number": "13",
        "name": "I6",
        "type": "input",
        "description": "Data input I6 of the 8-input multiplexer, selected when S2 is HIGH, S1 is HIGH and S0 is LOW with OE LOW; the input range is 0 V to VCC and clamp diodes allow current-limited interfacing to voltages above VCC."
      },
      {
        "number": "14",
        "name": "I5",
        "type": "input",
        "description": "Data input I5 of the 8-input multiplexer, selected when S2 is HIGH, S1 is LOW and S0 is HIGH with OE LOW; the input range is 0 V to VCC and clamp diodes allow current-limited interfacing to voltages above VCC."
      },
      {
        "number": "15",
        "name": "I4",
        "type": "input",
        "description": "Data input I4 of the 8-input multiplexer, selected when S2 is HIGH, S1 is LOW and S0 is LOW with OE LOW; the input range is 0 V to VCC and clamp diodes allow current-limited interfacing to voltages above VCC."
      },
      {
        "number": "16",
        "name": "VCC",
        "type": "power_in",
        "description": "Supply voltage; the recommended range is 2.0 V to 6.0 V for 74HC251 and 4.5 V to 5.5 V for 74HCT251, with absolute maximum 7 V."
      }
    ],
    "provenance": {
      "extractor": "extract_pins 0.3",
      "factory_chain": {
        "factory": "2.0.0",
        "extractor": "extract_pins 0.3",
        "primary_model": "claude-haiku-5-5",
        "primary_mode": "text",
        "consensus_model": "claude-sonnet-5-5",
        "consensus": "agreed",
        "guards": "pin_guards 0.1: passed",
        "guard_notes": [
          "extractor flagged: Polarity conflict in the datasheet: Table 2 describes OE as 'active LOW', but Section 1 says a HIGH ; The extracted text drops the overbar on the complementary output, so the name is shown as ~{Y} using; Pin numbers come from Table 2 and match the SO16 pin configuration in Fig. 4 (SOT109-1), which is th"
        ],
        "pages_sent": 16,
        "cost_usd": 0.077,
        "at": "2026-10-18T04:57:42"
      },
      "datasheet": {
        "url": "https://assets.nexperia.com/documents/data-sheet/74HC251D.pdf",
        "pages": 16,
        "sha256": "548cffe1beed1ca5",
        "source_tier": "mfr"
      },
      "cad": "KiCad official (CC-BY-SA 4.0)",
      "pins": {
        "total": 16,
        "described": 16,
        "cites_pages": true,
        "refuses_to_fabricate": true
      }
    },
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}