SN74HC42 BCD-to-Decimal Decoder

{
  "schema_version": 1,
  "type": "component",
  "slug": "sn74hc42",
  "title": "SN74HC42 BCD-to-Decimal Decoder",
  "brief": "BCD-to-decimal (1-of-10) decoder with active-low outputs, 74HC CMOS.",
  "version": "0.1.0",
  "license": "CC-BY-SA-4.0",
  "tags": [
    "logic",
    "decoder",
    "bcd",
    "74hc",
    "ti",
    "soic-16"
  ],
  "component": {
    "mpn": "SN74HC42",
    "manufacturer": "Texas Instruments",
    "package": "SOIC-16",
    "pin_count": 16,
    "category": "Logic",
    "subcategory": "Decoder / Demultiplexer",
    "datasheet": "https://www.ti.com/lit/ds/symlink/cd74hc42.pdf",
    "parts": {
      "symbol": "sn74hc42.kicad_sym",
      "footprint": "sn74hc42.kicad_mod",
      "model_3d": "sn74hc42-etched.glb",
      "model_3d_plain": "sn74hc42.glb",
      "model_3d_step": "sn74hc42-etched.step",
      "model_3d_step_plain": "sn74hc42.step",
      "lbr": "sn74hc42.lbr"
    },
    "distributor_links": {},
    "pins": [
      {
        "number": "1",
        "name": "Y0",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 0000. LOW when A3:A0 = 0; otherwise HIGH. LSTTL fan-out: 10 loads."
      },
      {
        "number": "2",
        "name": "Y1",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 0001."
      },
      {
        "number": "3",
        "name": "Y2",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 0010."
      },
      {
        "number": "4",
        "name": "Y3",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 0011."
      },
      {
        "number": "5",
        "name": "Y4",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 0100."
      },
      {
        "number": "6",
        "name": "Y5",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 0101."
      },
      {
        "number": "7",
        "name": "Y6",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 0110."
      },
      {
        "number": "8",
        "name": "GND",
        "type": "power_in",
        "description": "Ground reference (0 V)."
      },
      {
        "number": "9",
        "name": "Y7",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 0111."
      },
      {
        "number": "10",
        "name": "Y8",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 1000."
      },
      {
        "number": "11",
        "name": "Y9",
        "type": "output",
        "description": "Active-LOW decoded output for BCD input 1001."
      },
      {
        "number": "12",
        "name": "A3",
        "type": "input",
        "description": "BCD address input, bit 3 (MSB). HC: VIH ≥ 3.15 V @ VCC=4.5 V; VIL ≤ 1.35 V. HCT: VIH ≥ 2 V, VIL ≤ 0.8 V @ VCC=4.5-5.5 V. Input leakage ≤ 1 µA."
      },
      {
        "number": "13",
        "name": "A2",
        "type": "input",
        "description": "BCD address input, bit 2."
      },
      {
        "number": "14",
        "name": "A1",
        "type": "input",
        "description": "BCD address input, bit 1."
      },
      {
        "number": "15",
        "name": "A0",
        "type": "input",
        "description": "BCD address input, bit 0 (LSB)."
      },
      {
        "number": "16",
        "name": "VCC",
        "type": "power_in",
        "description": "Positive supply. HC: 2-6 V. HCT: 4.5-5.5 V. Absolute max −0.5 V to 7 V. Quiescent ICC ≤ 8 µA typ (80 µA max over temp)."
      }
    ],
    "provenance": {
      "extractor": "ds2sf",
      "datasheet": {
        "url": "https://www.ti.com/lit/ds/symlink/cd74hc42.pdf",
        "pages": 12,
        "sha256": "adc98c4caa771189",
        "source_tier": "mfr"
      },
      "cad": "KiCad official (CC-BY-SA 4.0)",
      "pins": {
        "total": 16,
        "described": 16,
        "cites_pages": true,
        "refuses_to_fabricate": true
      }
    },
    "viewers": {
      "symbol": "viewers/symbol.html",
      "footprint": "viewers/footprint.html"
    },
    "logic": {
      "family_id": "74HC42",
      "logic_family": "74HC",
      "function_code": "42",
      "function_class": null,
      "function_name": null,
      "manufacturer": "Texas Instruments",
      "is_specialty": false
    },
    "models_3d": [
      {
        "file": "sn74hc42.step",
        "role": "plain",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          6,
          9.9,
          1.75
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "d5eeddb4c0b304dc61950919b126fc61d7586abd5f16ab71a2a79759ec6498bf",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      },
      {
        "file": "sn74hc42-etched.step",
        "role": "eda",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          6,
          9.9,
          1.75
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "5f8bc38986093ad76413f531b5694871574288f5f3fbc68ccfc0c23c235e57aa",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      }
    ]
  },
  "metadata": {
    "specs": {
      "Type": "BCD-to-decimal (1-of-10) decoder",
      "Logic family": "74HC (CMOS)",
      "Outputs": "10, active-low",
      "Supply voltage": "2 V to 6 V",
      "Propagation delay": "20 ns typ at 5 V",
      "Operating temperature": "-40 C to 85 C"
    }
  },
  "sections": [
    "hero",
    "viewers",
    "readme",
    "breadcrumbs",
    "info"
  ],
  "discovery_triggers": [
    "BCD to decimal",
    "1-of-10 decoder",
    "BCD decoder",
    "active-low decoder"
  ],
  "discovery_pitch": "Decode a 4-bit BCD input to one of ten active-low outputs in the fast 74HC family.",
  "author": {
    "name": "Ray"
  },
  "dependencies": {},
  "hero": {
    "type": "image",
    "path": "docs/hero.png"
  },
  "files": [
    "page.json",
    "README.md",
    "sn74hc42.kicad_sym",
    "sn74hc42.kicad_mod",
    "sn74hc42.glb",
    "sn74hc42.step",
    "sn74hc42.lbr",
    "docs/hero.png",
    "docs/sn74hc42-datasheet.pdf",
    "viewers/symbol.html",
    "viewers/footprint.html",
    "sn74hc42-etched.step"
  ],
  "variants": [
    {
      "mpn": "SN74HC42CD74HC42M",
      "kind": "unknown"
    },
    {
      "mpn": "SN74HC42CD74HC42M.A",
      "kind": "unknown"
    },
    {
      "mpn": "SN74HC42CD74HC42E",
      "kind": "unknown"
    },
    {
      "mpn": "SN74HC42CD74HC42E.A",
      "kind": "unknown"
    },
    {
      "mpn": "SN74HC42CD74HCT42E",
      "kind": "unknown"
    },
    {
      "mpn": "SN74HC42CD74HCT42E.A",
      "kind": "unknown"
    },
    {
      "mpn": "SN74HC42CD54HC42F3A",
      "kind": "unknown"
    },
    {
      "mpn": "SN74HC42CD54HC42F3A.A",
      "kind": "unknown"
    }
  ]
}