SN74HC138

{
  "schema_version": 1,
  "type": "component",
  "slug": "sn74hc138",
  "title": "SN74HC138",
  "brief": "TI 3-to-8 line decoder/demultiplexer, SOIC-16. Three enables, eight active-low outputs, HC CMOS 2-6 V. Datasheet-verified.",
  "version": "0.1.0",
  "license": "CC-BY-SA-4.0",
  "tags": [
    "component",
    "logic",
    "decoder",
    "demultiplexer",
    "74hc",
    "soic-16",
    "texas-instruments"
  ],
  "component": {
    "mpn": "SN74HC138",
    "manufacturer": "Texas Instruments",
    "package": "SOIC-16",
    "pin_count": 16,
    "category": "Logic IC",
    "subcategory": "3-to-8 line decoder / demux",
    "datasheet": "https://www.ti.com/lit/ds/symlink/sn74hc138.pdf",
    "parts": {
      "symbol": "sn74hc138.kicad_sym",
      "footprint": "sn74hc138.kicad_mod",
      "model_3d": "sn74hc138-etched.glb",
      "model_3d_plain": "sn74hc138.glb",
      "lbr": "sn74hc138.lbr",
      "model_3d_step": "sn74hc138-etched.step",
      "model_3d_step_plain": "sn74hc138.step"
    },
    "distributor_links": {},
    "pins": [
      {
        "number": "1",
        "name": "A",
        "type": "input",
        "description": "Select input A (least significant bit of the 3-bit binary address selecting which Y output is asserted low)."
      },
      {
        "number": "2",
        "name": "B",
        "type": "input",
        "description": "Select input B (middle bit of the 3-bit binary address)."
      },
      {
        "number": "3",
        "name": "C",
        "type": "input",
        "description": "Select input C (most significant bit of the 3-bit binary address)."
      },
      {
        "number": "4",
        "name": "G2A",
        "type": "input",
        "description": "Active-low enable A. Must be low (together with G2B low and G1 high) to enable outputs; otherwise all Y outputs are forced high."
      },
      {
        "number": "5",
        "name": "G2B",
        "type": "input",
        "description": "Active-low enable B. Must be low (together with G2A low and G1 high) to enable outputs."
      },
      {
        "number": "6",
        "name": "G1",
        "type": "input",
        "description": "Active-high enable. Must be high (together with G2A and G2B low) to enable outputs."
      },
      {
        "number": "7",
        "name": "Y7",
        "type": "output",
        "description": "Decoded output 7 (most significant, active low). Asserts low when enabled and CBA = 111. Drive capability ±4 mA at VCC = 5 V."
      },
      {
        "number": "8",
        "name": "GND",
        "type": "power_in",
        "description": "Ground reference (0 V)."
      },
      {
        "number": "9",
        "name": "Y6",
        "type": "output",
        "description": "Decoded output 6 (active low). Asserts low when enabled and CBA = 110."
      },
      {
        "number": "10",
        "name": "Y5",
        "type": "output",
        "description": "Decoded output 5 (active low). Asserts low when enabled and CBA = 101."
      },
      {
        "number": "11",
        "name": "Y4",
        "type": "output",
        "description": "Decoded output 4 (active low). Asserts low when enabled and CBA = 100."
      },
      {
        "number": "12",
        "name": "Y3",
        "type": "output",
        "description": "Decoded output 3 (active low). Asserts low when enabled and CBA = 011."
      },
      {
        "number": "13",
        "name": "Y2",
        "type": "output",
        "description": "Decoded output 2 (active low). Asserts low when enabled and CBA = 010."
      },
      {
        "number": "14",
        "name": "Y1",
        "type": "output",
        "description": "Decoded output 1 (active low). Asserts low when enabled and CBA = 001."
      },
      {
        "number": "15",
        "name": "Y0",
        "type": "output",
        "description": "Decoded output 0 (least significant, active low). Asserts low when enabled and CBA = 000."
      },
      {
        "number": "16",
        "name": "VCC",
        "type": "power_in",
        "description": "Positive supply voltage, 2 V to 6 V (nominal 5 V)."
      }
    ],
    "provenance": {
      "extractor": "ds2sf",
      "datasheet": {
        "url": "https://www.ti.com/lit/ds/symlink/sn74hc138.pdf",
        "pages": 35,
        "sha256": "ba6cab88a44c1c9a",
        "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": "74HC138",
      "logic_family": "74HC",
      "function_code": "138",
      "function_class": "Decoder",
      "function_name": "3-to-8 Line Decoder/Demultiplexer",
      "manufacturer": "Texas Instruments",
      "is_specialty": false
    },
    "models_3d": [
      {
        "file": "sn74hc138.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": "sn74hc138-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": "f2e0f9af5f7909f5e497cbcfc33314b7f8513a88f72ad0e9522cfa2b5257de2a",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      }
    ]
  },
  "metadata": {
    "specs": {
      "Type": "3-to-8 decoder / demultiplexer",
      "Select inputs": "3 (A/B/C)",
      "Outputs": "8 active-low (Y0-Y7)",
      "Enables": "G1 (high) + G2A/G2B (low)",
      "Logic family": "HC (high-speed CMOS)",
      "Supply voltage": "2-6 V",
      "Package": "SOIC-16",
      "Body (L×W×H)": "9.9 × 3.9 × 1.75 mm"
    }
  },
  "sections": [
    "hero",
    "viewers",
    "readme",
    "breadcrumbs",
    "info"
  ],
  "discovery_triggers": [
    "sn74hc138",
    "74hc138",
    "3 to 8 decoder",
    "address decoder",
    "demultiplexer"
  ],
  "discovery_pitch": "SN74HC138 3-to-8 line decoder/demultiplexer (SOIC-16) with datasheet-verified pinout, KiCad symbol/footprint/3D, and full provenance.",
  "author": {
    "name": "Ray"
  },
  "dependencies": {},
  "hero": {
    "type": "image",
    "path": "docs/hero.png"
  },
  "files": [
    "page.json",
    "README.md",
    "sn74hc138.kicad_sym",
    "sn74hc138.kicad_mod",
    "sn74hc138.glb",
    "sn74hc138.lbr",
    "docs/hero.png",
    "docs/sn74hc138-datasheet.pdf",
    "viewers/symbol.html",
    "viewers/footprint.html",
    "sn74hc138-etched.step"
  ],
  "variants": [
    {
      "mpn": "SN74HC138D (SOIC-16, tube)",
      "kind": "packaging"
    },
    {
      "mpn": "SN74HC138DR (SOIC-16, tape & reel)",
      "kind": "packaging"
    }
  ]
}