PCA9557

{
  "schema_version": 1,
  "type": "component",
  "slug": "pca9557",
  "title": "PCA9557",
  "brief": "TI 8-bit I2C I/O expander with reset, HVQFN-16. Eight I/O, hardware RESET, 8 addresses, 2.3-5.5 V. Datasheet-verified.",
  "version": "0.1.0",
  "license": "CC-BY-SA-4.0",
  "tags": [
    "component",
    "interface",
    "io-expander",
    "gpio-expander",
    "i2c",
    "hvqfn-16",
    "texas-instruments"
  ],
  "component": {
    "mpn": "PCA9557",
    "manufacturer": "Texas Instruments",
    "package": "HVQFN-16",
    "pin_count": 16,
    "category": "Interface",
    "subcategory": "I2C I/O expander",
    "datasheet": "https://www.ti.com/lit/ds/symlink/pca9557.pdf",
    "parts": {
      "symbol": "pca9557.kicad_sym",
      "footprint": "pca9557.kicad_mod",
      "model_3d": "pca9557-etched.glb",
      "model_3d_plain": "pca9557.glb",
      "model_3d_step": "pca9557-etched.step",
      "model_3d_step_plain": "pca9557.step",
      "lbr": "pca9557.lbr"
    },
    "distributor_links": {},
    "pins": [
      {
        "number": "1",
        "name": "A0",
        "type": "input",
        "description": "Hardware I2C address input bit 0. Tie directly to VCC or GND to program the device's I2C slave address (up to 8 devices per bus)."
      },
      {
        "number": "2",
        "name": "A1",
        "type": "input",
        "description": "Hardware I2C address input bit 1. Tie directly to VCC or GND."
      },
      {
        "number": "3",
        "name": "A2",
        "type": "input",
        "description": "Hardware I2C address input bit 2. Tie directly to VCC or GND."
      },
      {
        "number": "4",
        "name": "IO0",
        "type": "bidirectional",
        "description": "P-port I/O bit 0. High-impedance open-drain output structure; requires an external pullup to VCC when driven high. Configured as input at power-on."
      },
      {
        "number": "5",
        "name": "IO1",
        "type": "bidirectional",
        "description": "P-port I/O bit 1. Push-pull output; sinks up to 25 mA to drive LEDs directly. Input at power-on."
      },
      {
        "number": "6",
        "name": "VSS",
        "type": "power_in",
        "description": "Ground reference for supply and I/O."
      },
      {
        "number": "7",
        "name": "IO2",
        "type": "bidirectional",
        "description": "P-port I/O bit 2. Push-pull output; 25 mA sink capability. Input at power-on."
      },
      {
        "number": "8",
        "name": "IO3",
        "type": "bidirectional",
        "description": "P-port I/O bit 3. Push-pull output; 25 mA sink capability. Input at power-on."
      },
      {
        "number": "9",
        "name": "IO4",
        "type": "bidirectional",
        "description": "P-port I/O bit 4. Push-pull output; 25 mA sink capability. Input at power-on."
      },
      {
        "number": "10",
        "name": "IO5",
        "type": "bidirectional",
        "description": "P-port I/O bit 5. Push-pull output; 25 mA sink capability. Input at power-on."
      },
      {
        "number": "11",
        "name": "IO6",
        "type": "bidirectional",
        "description": "P-port I/O bit 6. Push-pull output; 25 mA sink capability. Input at power-on."
      },
      {
        "number": "12",
        "name": "IO7",
        "type": "bidirectional",
        "description": "P-port I/O bit 7. Push-pull output; 25 mA sink capability. Input at power-on."
      },
      {
        "number": "13",
        "name": "RESET",
        "type": "input",
        "description": "Active-low reset input. Asserting low reinitializes the registers and I2C/SMBus state machine. Tie to VCC through a pullup if unused."
      },
      {
        "number": "14",
        "name": "VDD",
        "type": "power_in",
        "description": "Supply voltage, 2.3 V to 5.5 V. Decouple with a 0.1 µF ceramic capacitor to GND close to the pin."
      },
      {
        "number": "15",
        "name": "SCL",
        "type": "input",
        "description": "I2C serial clock input. Requires an external pullup resistor to VCC. Supports 100 kHz standard mode and 400 kHz fast mode."
      },
      {
        "number": "16",
        "name": "SDA",
        "type": "bidirectional",
        "description": "I2C serial data line, open-drain bidirectional. Requires an external pullup resistor to VCC."
      }
    ],
    "provenance": {
      "extractor": "ds2sf",
      "datasheet": {
        "url": "https://www.ti.com/lit/ds/symlink/pca9557.pdf",
        "pages": 47,
        "sha256": "d55cbe207fbcb26d",
        "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"
    },
    "models_3d": [
      {
        "file": "pca9557.step",
        "role": "plain",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          3,
          3,
          0.775
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "864b2e2baff7c06a8eb6f8bb89e505f76c65965b4fd8a7ef4fb7d405647c3957",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      },
      {
        "file": "pca9557-etched.step",
        "role": "eda",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          3,
          3,
          0.775
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "eb1cbbefaeacaef675735d51f1bd70d045fb91e48acc4176d07ee0665ba1cfce",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      }
    ]
  },
  "metadata": {
    "specs": {
      "Type": "8-bit I2C I/O expander",
      "Interface": "I2C (up to 400 kHz)",
      "I/O": "8 pins (IO0-IO7)",
      "Reset": "Hardware RESET input",
      "Polarity": "Per-pin inversion register",
      "Addresses": "8 (A0-A2)",
      "Supply": "2.3-5.5 V",
      "Package": "HVQFN-16"
    }
  },
  "sections": [
    "hero",
    "viewers",
    "readme",
    "breadcrumbs",
    "info"
  ],
  "discovery_triggers": [
    "pca9557",
    "8-bit io expander",
    "i2c gpio with reset",
    "add gpio over i2c"
  ],
  "discovery_pitch": "TI PCA9557 8-bit I2C I/O expander with reset (HVQFN-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",
    "pca9557.kicad_sym",
    "pca9557.kicad_mod",
    "pca9557.glb",
    "pca9557.step",
    "pca9557.lbr",
    "docs/hero.png",
    "docs/pca9557-datasheet.pdf",
    "viewers/symbol.html",
    "viewers/footprint.html",
    "pca9557-etched.step"
  ],
  "variants": [
    {
      "mpn": "PCA9557PW (TSSOP-16)",
      "kind": "packaging"
    },
    {
      "mpn": "PCA9557BS (HVQFN-16)",
      "kind": "packaging"
    },
    {
      "mpn": "PCA9557D (SOIC-16)",
      "kind": "packaging"
    }
  ]
}