PCF8574

{
  "schema_version": 1,
  "type": "component",
  "slug": "pcf8574",
  "title": "PCF8574",
  "brief": "TI remote 8-bit I2C I/O expander, SOIC-16. Eight quasi-bidirectional lines, 3 address pins, open-drain INT. Datasheet-verified.",
  "version": "0.1.3",
  "license": "CC-BY-SA-4.0",
  "tags": [
    "component",
    "interface",
    "io-expander",
    "i2c",
    "gpio",
    "soic-16",
    "texas-instruments"
  ],
  "component": {
    "mpn": "PCF8574",
    "manufacturer": "Texas Instruments",
    "package": "SOIC-16",
    "pin_count": 16,
    "category": "Interface IC",
    "subcategory": "I2C 8-bit I/O expander",
    "datasheet": "https://www.ti.com/lit/ds/symlink/pcf8574.pdf",
    "parts": {
      "symbol": "pcf8574.kicad_sym",
      "footprint": "pcf8574.kicad_mod",
      "model_3d": "pcf8574-etched.glb",
      "model_3d_plain": "pcf8574.glb",
      "lbr": "pcf8574.lbr",
      "model_3d_step": "pcf8574-etched.step",
      "model_3d_step_plain": "pcf8574.step"
    },
    "distributor_links": {},
    "pins": [
      {
        "number": "1",
        "name": "A0",
        "type": "input",
        "description": "Hardware I2C slave-address input bit 0. Tie directly to VCC or GND; no pullup required. Sets the lower address bits so up to eight PCF8574 devices can share the same bus."
      },
      {
        "number": "2",
        "name": "A1",
        "type": "input",
        "description": "Hardware I2C slave-address input bit 1. Tie directly to VCC or GND; no pullup required."
      },
      {
        "number": "3",
        "name": "A2",
        "type": "input",
        "description": "Hardware I2C slave-address input bit 2. Tie directly to VCC or GND; no pullup required."
      },
      {
        "number": "4",
        "name": "P0",
        "type": "bidirectional",
        "description": "Quasi-bidirectional I/O port bit 0. Push-pull structure with a latched output; can drive LEDs directly (100 mA/pin, JESD 78 Class II latch-up). High at power-up (input mode with weak current source to VCC)."
      },
      {
        "number": "5",
        "name": "P1",
        "type": "bidirectional",
        "description": "Quasi-bidirectional I/O port bit 1. See P0 for drive characteristics."
      },
      {
        "number": "6",
        "name": "P2",
        "type": "bidirectional",
        "description": "Quasi-bidirectional I/O port bit 2. See P0 for drive characteristics."
      },
      {
        "number": "7",
        "name": "P3",
        "type": "bidirectional",
        "description": "Quasi-bidirectional I/O port bit 3. See P0 for drive characteristics."
      },
      {
        "number": "8",
        "name": "GND",
        "type": "power_in",
        "description": "Ground reference. 0 V return for the supply and I/O."
      },
      {
        "number": "9",
        "name": "P4",
        "type": "bidirectional",
        "description": "Quasi-bidirectional I/O port bit 4. See P0 for drive characteristics."
      },
      {
        "number": "10",
        "name": "P5",
        "type": "bidirectional",
        "description": "Quasi-bidirectional I/O port bit 5. See P0 for drive characteristics."
      },
      {
        "number": "11",
        "name": "P6",
        "type": "bidirectional",
        "description": "Quasi-bidirectional I/O port bit 6. See P0 for drive characteristics."
      },
      {
        "number": "12",
        "name": "P7",
        "type": "bidirectional",
        "description": "Quasi-bidirectional I/O port bit 7. See P0 for drive characteristics."
      },
      {
        "number": "13",
        "name": "INT",
        "type": "output",
        "description": "Open-drain interrupt output, active-low. Asserts when a P-port input changes state; requires an external pullup resistor to VCC. Interrupt reset delay (t_ir) is 4 µs max after SCL toggle."
      },
      {
        "number": "14",
        "name": "SCL",
        "type": "input",
        "description": "I2C serial clock line. Requires an external pullup resistor to VCC. Supports 100 kHz standard-mode I2C timing."
      },
      {
        "number": "15",
        "name": "SDA",
        "type": "bidirectional",
        "description": "I2C serial data line, open-drain. Requires an external pullup resistor to VCC. Carries device address and P-port read/write data."
      },
      {
        "number": "16",
        "name": "VCC",
        "type": "power_in",
        "description": "Positive supply voltage, 2.5 V to 6 V (recommended). Standby ICC = 2.5 µA typ; operating ICC = 40 µA typ at 100 kHz SCL."
      }
    ],
    "provenance": {
      "extractor": "ds2sf",
      "datasheet": {
        "url": "https://www.ti.com/lit/ds/symlink/pcf8574.pdf",
        "pages": 42,
        "sha256": "4e4cb9144f852941",
        "source_tier": "mfr"
      },
      "cad": "KiCad official (CC-BY-SA 4.0)",
      "pins": {
        "total": 16,
        "described": 16,
        "cites_pages": true,
        "refuses_to_fabricate": true
      },
      "review_fix": {
        "at": "2026-11-10",
        "by": "part-reviewer (Ray review)",
        "what": "pin names set to the maker spelling from TI SCPS068K Figure 4-4 (DW, 16 pins) and Pin Functions table: 0 on the page, 2 on the symbol (numbers unchanged)."
      }
    },
    "viewers": {
      "symbol": "viewers/symbol.html",
      "footprint": "viewers/footprint.html"
    },
    "models_3d": [
      {
        "file": "pcf8574.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": "2026-11-10",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      },
      {
        "file": "pcf8574-etched.step",
        "role": "plain",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          6,
          9.9,
          1.78
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "811ee094c3774ebf38ca00231acdfd140350765b02ffb30ebee2a0c2bb6ff68c",
        "checked": "2026-11-10",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      }
    ]
  },
  "metadata": {
    "specs": {
      "Type": "I2C 8-bit I/O expander",
      "I/O lines": "8 quasi-bidirectional (P0-P7)",
      "Bus": "I2C (two-wire), up to 100 kHz",
      "Address pins": "A0-A2 (8 per bus)",
      "Interrupt": "open-drain INT on change",
      "Direction register": "none (write-high to read)",
      "Supply voltage": "2.5-6 V",
      "Package": "SOIC-16"
    }
  },
  "sections": [
    "hero",
    "viewers",
    "readme",
    "breadcrumbs",
    "info"
  ],
  "discovery_triggers": [
    "pcf8574",
    "i2c io expander",
    "gpio expander",
    "i2c port expander",
    "lcd backpack chip"
  ],
  "discovery_pitch": "PCF8574 remote 8-bit I2C I/O expander (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",
    "pcf8574.kicad_sym",
    "pcf8574.kicad_mod",
    "pcf8574.glb",
    "pcf8574.lbr",
    "docs/hero.png",
    "docs/pcf8574-datasheet.pdf",
    "viewers/symbol.html",
    "viewers/footprint.html",
    "pcf8574-etched.step",
    "pcf8574-etched.glb",
    "pcf8574.step"
  ],
  "variants": [
    {
      "mpn": "PCF8574T (SOIC-16, tube)",
      "kind": "packaging"
    },
    {
      "mpn": "PCF8574TR (SOIC-16, tape & reel)",
      "kind": "packaging"
    }
  ],
  "description": "TI remote 8-bit I2C I/O expander, SOIC-16. Eight quasi-bidirectional lines, 3 address pins, open-drain INT. Datasheet-verified.",
  "org": "adom"
}