UC3845B

{
  "schema_version": 1,
  "type": "component",
  "slug": "uc3845b",
  "title": "UC3845B",
  "brief": "UMW AC-DC Controllers and Regulators, SOP-8. Pinout extracted from the datasheet, KiCad symbol/footprint/3D.",
  "version": "0.2.0",
  "license": "CC-BY-SA-4.0",
  "tags": [
    "component",
    "pmic",
    "uc3845b"
  ],
  "component": {
    "mpn": "UC3845B",
    "manufacturer": "UMW",
    "package": "SOP-8",
    "pin_count": 8,
    "category": "PMIC",
    "subcategory": "AC-DC Controllers and Regulators",
    "datasheet": "https://datasheet.lcsc.com/datasheet/pdf/e3d63309cbe1c8f3cf586cb6af3a803e.pdf",
    "parts": {
      "symbol": "uc3845b.kicad_sym",
      "footprint": "uc3845b.kicad_mod",
      "model_3d": "uc3845b-etched.glb",
      "model_3d_plain": "uc3845b.glb",
      "model_3d_step": "uc3845b-etched.step",
      "model_3d_step_plain": "uc3845b.step",
      "lbr": "uc3845b.lbr"
    },
    "distributor_links": {
      "lcsc": "C347460"
    },
    "pins": [
      {
        "number": "1",
        "name": "COMP",
        "type": "output",
        "description": "Error Amplifier output pin, used for external loop compensation. Typical high output voltage 5-6 V, low output 0.8-1.1 V (with 15 kΩ load)."
      },
      {
        "number": "2",
        "name": "VFB",
        "type": "input",
        "description": "Inverting input of the Error Amplifier. Normally connected to the switching power supply output through a resistor divider; internal reference at 2.5 V (typ). Input bias current -0.1 µA typ."
      },
      {
        "number": "3",
        "name": "ISENSE",
        "type": "input",
        "description": "Current sense input. A voltage proportional to the inductor current (up to ~1 V max) is applied here; the PWM comparator uses this to terminate output switch conduction each cycle. Input voltage range -0.3 to 5.5 V max."
      },
      {
        "number": "4",
        "name": "RT/CT",
        "type": "passive",
        "description": "Oscillator timing pin. Oscillator frequency and maximum output duty cycle are set by connecting a timing resistor RT from VREF to this pin and a timing capacitor CT from this pin to ground. Operating frequency up to 500 kHz."
      },
      {
        "number": "5",
        "name": "GND",
        "type": "power_in",
        "description": "Combined control circuitry and power ground return for the IC."
      },
      {
        "number": "6",
        "name": "OUT",
        "type": "output",
        "description": "Totem-pole gate drive output for an external power MOSFET. Sources/sinks peak currents up to 1 A. VOH ≈ 13-13.5 V, VOL ≈ 0.08-1.4 V depending on load; rise/fall time ~35-45 ns into 1 nF."
      },
      {
        "number": "7",
        "name": "VCC",
        "type": "power_in",
        "description": "Positive supply for the IC. UVLO start threshold 8.4 V typ (7.8-9 V), min operating 7.6 V typ (7-8.2 V) after turn-on. Absolute max 30 V; zener clamp ≈ 30-38 V at 25 mA. Operating supply current 13 mA typ; start-up current 0.5 mA typ."
      },
      {
        "number": "8",
        "name": "VREF",
        "type": "power_out",
        "description": "Internal 5 V reference output (4.9-5.1 V), used to charge timing capacitor CT through timing resistor RT and to bias external circuitry. Short-circuit current typically -100 mA (limited to -180 mA max). Load current 1-20 mA."
      }
    ],
    "provenance": {
      "extractor": "ds2sf",
      "datasheet": {
        "url": "https://datasheet.lcsc.com/datasheet/pdf/e3d63309cbe1c8f3cf586cb6af3a803e.pdf",
        "pages": 13,
        "sha256": "562bc6cb07a3fb91",
        "source_tier": "lcsc"
      },
      "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"
    },
    "pin1": {
      "pad": "1",
      "at": [
        -2.475,
        -1.905
      ],
      "corner": "top-left",
      "source": "silk-marker",
      "derived_from": "SOIC-8_3.9x4.9mm_P1.27mm@sha256:074ecb2092b24fa4",
      "mark": "drawn"
    },
    "models_3d": [
      {
        "file": "uc3845b.step",
        "role": "plain",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          6,
          4.9,
          1.75
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "07f46cff378d30e6c27dfd5a03092c795323f86d91c71fc7e743f4f418dc553a",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      },
      {
        "file": "uc3845b-etched.step",
        "role": "eda",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "z = 0",
        "extents_mm": [
          6,
          4.9,
          1.75
        ],
        "zmin_mm": 0,
        "centre_offset_mm": 0,
        "footprint_binding": "identity",
        "sha256": "85394355d281089895029b09067a84779c7ecd8358463fab07e98b19eefcbc30",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      }
    ]
  },
  "metadata": {
    "specs": {
      "Manufacturer": "UMW",
      "Package": "SOP-8",
      "Category": "PMIC",
      "Pins": "8"
    }
  },
  "sections": [
    "hero",
    "viewers",
    "readme",
    "breadcrumbs",
    "info"
  ],
  "discovery_triggers": [
    "uc3845b"
  ],
  "discovery_pitch": "UC3845B (UMW) component page with datasheet-verified CAD.",
  "author": {
    "name": "Ray"
  },
  "dependencies": {},
  "hero": {
    "type": "image",
    "path": "docs/hero.png"
  },
  "files": [
    "page.json",
    "README.md",
    "uc3845b.kicad_sym",
    "uc3845b.kicad_mod",
    "uc3845b.glb",
    "uc3845b.step",
    "uc3845b-etched.step",
    "uc3845b.lbr",
    "docs/hero.png",
    "docs/uc3845b-datasheet.pdf",
    "viewers/symbol.html",
    "viewers/footprint.html"
  ],
  "visibility": {
    "public": true
  },
  "variants": [
    {
      "mpn": "UC3845B",
      "kind": "packaging"
    }
  ],
  "updated_at": "2026-09-25T13:32:31.090Z"
}