DS1307

{
  "schema_version": 1,
  "type": "component",
  "slug": "ds1307",
  "title": "DS1307",
  "brief": "Analog Devices I2C real-time clock, DIP-8. BCD time/date, 56 B NVRAM, battery backup, square-wave out. Datasheet-verified.",
  "version": "0.1.0",
  "license": "CC-BY-SA-4.0",
  "tags": [
    "component",
    "clock",
    "rtc",
    "real-time-clock",
    "i2c",
    "dip-8",
    "analog-devices"
  ],
  "component": {
    "mpn": "DS1307",
    "manufacturer": "Analog Devices",
    "package": "PDIP-8",
    "pin_count": 8,
    "category": "Clock IC",
    "subcategory": "I2C real-time clock",
    "datasheet": "https://cdn.sparkfun.com/datasheets/BreakoutBoards/DS1307.pdf",
    "parts": {
      "symbol": "ds1307.kicad_sym",
      "footprint": "ds1307.kicad_mod",
      "model_3d": "ds1307-etched.glb",
      "model_3d_plain": "ds1307.glb",
      "lbr": "ds1307.lbr",
      "model_3d_step": "ds1307-etched.step",
      "model_3d_step_plain": "ds1307.step"
    },
    "distributor_links": {},
    "pins": [
      {
        "number": "1",
        "name": "X1",
        "type": "input",
        "description": "Connection for a standard 32.768kHz quartz crystal (C_L = 12.5pF). X1 is the input to the internal oscillator and can optionally be connected to an external 32.768kHz oscillator (with X2 left floating)."
      },
      {
        "number": "2",
        "name": "X2",
        "type": "output",
        "description": "Connection for the second terminal of the 32.768kHz quartz crystal. X2 is the output of the internal oscillator; leave floating if an external oscillator drives X1."
      },
      {
        "number": "3",
        "name": "VBAT",
        "type": "power_in",
        "description": "Backup supply input for a standard 3V lithium cell or other energy source (2.0V to 3.5V, typ 3V). Powers the RTC and SRAM when VCC is removed; must be grounded if a backup supply is not used. Nominal power-fail trip point is 1.25 x VBAT."
      },
      {
        "number": "4",
        "name": "GND",
        "type": "power_in",
        "description": "Device ground reference. All voltages are referenced to this pin."
      },
      {
        "number": "5",
        "name": "SDA",
        "type": "bidirectional",
        "description": "I2C serial data input/output. Open-drain output requiring an external pullup resistor; pullup voltage may be up to 5.5V regardless of VCC. Bus capacitance is limited to 400pF and pin capacitance is <=10pF."
      },
      {
        "number": "6",
        "name": "SCL",
        "type": "input",
        "description": "I2C serial clock input (0 to 100kHz). Synchronizes data movement on the serial interface. Requires an external pullup resistor; pullup voltage may be up to 5.5V regardless of VCC."
      },
      {
        "number": "7",
        "name": "SQW/OUT",
        "type": "output",
        "description": "Square-wave / output driver. When SQWE is set to 1, drives one of four square-wave frequencies (1Hz, 4kHz, 8kHz, 32kHz). Open-drain output requiring an external pullup (up to 5.5V); operates from either VCC or VBAT. May be left floating if unused."
      },
      {
        "number": "8",
        "name": "VCC",
        "type": "power_in",
        "description": "Primary power supply (4.5V to 5.5V, typ 5.0V). Full read/write access to the device is enabled when VCC is within operating range; when VCC falls below 1.25 x VBAT the device switches to battery-backup mode and timekeeping continues from VBAT."
      }
    ],
    "provenance": {
      "extractor": "ds2sf",
      "datasheet": {
        "url": "https://cdn.sparkfun.com/datasheets/BreakoutBoards/DS1307.pdf",
        "pages": 14,
        "sha256": "4114781b89b9a71a",
        "source_tier": "mfr"
      },
      "cad": "KiCad official (CC-BY-SA 4.0)",
      "pins": {
        "total": 8,
        "described": 8,
        "cites_pages": true,
        "refuses_to_fabricate": true
      }
    },
    "viewers": {
      "symbol": "viewers/symbol.html",
      "footprint": "viewers/footprint.html"
    },
    "models_3d": [
      {
        "file": "ds1307.step",
        "role": "plain",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "body on z = 0, through-hole leads below",
        "extents_mm": [
          7.874,
          9.27,
          6.98
        ],
        "zmin_mm": -3.3,
        "centre_offset_mm": 0.0,
        "footprint_binding": "identity",
        "sha256": "4a377a56a8d9e9c0b86c095ef9ecc1869ac19e7f5069a3247b294250bf4f235d",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      },
      {
        "file": "ds1307-etched.step",
        "role": "eda",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "body on z = 0, through-hole leads below",
        "extents_mm": [
          7.874,
          9.27,
          6.98
        ],
        "zmin_mm": -3.3,
        "centre_offset_mm": 0.0,
        "footprint_binding": "identity",
        "sha256": "af4ae2ded1d62330f1f29ecf418d5a954b6f45d4a2a748be1db7aeb08ad8b593",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      }
    ]
  },
  "metadata": {
    "specs": {
      "Type": "I2C real-time clock (RTC)",
      "Timekeeping": "seconds to year, BCD, leap-year",
      "NVRAM": "56 bytes general-purpose",
      "Backup": "VBAT coin-cell (keeps running)",
      "Interface": "I2C",
      "Timebase": "external 32.768 kHz crystal",
      "Output": "programmable square wave (1 Hz-32 kHz)",
      "Package": "PDIP-8"
    }
  },
  "sections": [
    "hero",
    "viewers",
    "readme",
    "breadcrumbs",
    "info"
  ],
  "discovery_triggers": [
    "ds1307",
    "real time clock",
    "i2c rtc",
    "rtc chip",
    "tiny rtc"
  ],
  "discovery_pitch": "DS1307 I2C real-time clock (DIP-8, battery-backed) with datasheet-verified pinout, KiCad symbol/footprint/3D, and full provenance.",
  "author": {
    "name": "Ray",
    "email": "[email protected]"
  },
  "dependencies": {},
  "hero": {
    "type": "image",
    "path": "docs/hero.png"
  },
  "files": [
    "page.json",
    "README.md",
    "ds1307.kicad_sym",
    "ds1307.kicad_mod",
    "ds1307.glb",
    "ds1307.lbr",
    "docs/hero.png",
    "docs/ds1307-datasheet.pdf",
    "viewers/symbol.html",
    "viewers/footprint.html",
    "ds1307-etched.step"
  ],
  "variants": [
    {
      "mpn": "DS1307N+ (PDIP-8)",
      "kind": "packaging"
    },
    {
      "mpn": "DS1307Z+ (SOIC-8)",
      "kind": "packaging"
    }
  ]
}