PCF8523 Real-Time Clock

@@ -0,0 +1,56 @@+# PCF8523++**NXP** · Real-Time Clock (RTC) · SOIC-8++The PCF8523 is a low-power CMOS real-time clock and calendar with an I2C interface. It tracks seconds through year with leap-year compensation, runs from a backup battery when main power is off, and provides programmable alarm, timer, and clock-output functions. It suits battery-backed timekeeping in metering, logging, and embedded systems.++## Pinout++| Pin | Name | Type | Function |+|---|---|---|---|+| 1 | OSCI | input | 32.768 kHz crystal oscillator input; high-impedance node. Connect to one terminal of the 32.768 kHz quartz crystal; internal load capacitors are selectable (7 pF or 12.5 pF via CAP_SEL). Keep wire length between quartz and package minimal. |+| 2 | OSCO | output | 32.768 kHz crystal oscillator output; high-impedance node. Connect to the other terminal of the 32.768 kHz quartz crystal. |+| 3 | VBAT | power_in | Battery supply voltage input. Feeds the on-chip battery switch-over circuit which automatically supplies the RTC from the backup battery when VDD drops. |+| 4 | VSS | power_in | Ground supply voltage (0 V reference). |+| 5 | SDA | bidirectional | I²C-bus serial data input/output. Open-drain; requires external pull-up resistor. Supports Fast-mode Plus up to 1 MHz. |+| 6 | SCL | input | I²C-bus serial clock input. Requires external pull-up resistor. Supports Fast-mode Plus up to 1 MHz. |+| 7 | INT1/CLKOUT | output | Interrupt 1 / clock output (open-drain). Selectable via register: either drives the active-LOW INT1 interrupt (alarm/timer/second) or the programmable CLKOUT (32.768 kHz / 16.384 kHz / 8.192 kHz / 4.096 kHz / 1.024 kHz / 32 Hz / 1 Hz). Requires external pull-up. |+| 8 | VDD | power_in | Main supply voltage input. Operating range 1.0 V to 5.5 V; typical backup current 150 nA at VDD = 3.0 V, Tamb = 25 °C. |++## Key specifications++| Parameter | Value |+|---|---|+| Type | I2C real-time clock / calendar |+| Interface | I2C (up to 1 MHz) |+| Timekeeping | Seconds to year, leap-year compensated |+| Backup | Battery switch-over |+| Features | Alarm, timer, programmable clock output |+| Supply voltage | 1.8 V to 5.5 V |+| Operating temperature | -40 C to 85 C |++## Ordering variants++- `PCF8523T`+- `PCF8523T/1`+- `PCF8523TK`+- `PCF8523TK/1`+- `PCF8523TS`+- `PCF8523TS/1`+- `PCF8523U/12AA/1`++## CAD (KiCad official)++- Symbol: `pcf8523.kicad_sym`+- Footprint: `pcf8523.kicad_mod`+- 3D model: SOIC-8 body from KiCad `Package_SO/SOIC-8_3.9x4.9mm_P1.27mm`.++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [NXP datasheet](https://www.nxp.com/docs/en/data-sheet/PCF8523.pdf) (78 pp, sha256 `409cb5ca8b0d04bc`, retrieved 2026-08-17, tier: manufacturer)+- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.+- **CAD:** KiCad official libraries (CC-BY-SA 4.0).++[Datasheet PDF](docs/pcf8523-datasheet.pdf)

@@ -0,0 +1,37 @@+{+  "slug": "pcf8523",+  "version": "0.1.0",+  "type": "component",+  "description": "Low-power I2C real-time clock and calendar with battery backup and alarm.",+  "tags": [+    "rtc",+    "real-time-clock",+    "i2c",+    "calendar",+    "low-power",+    "nxp",+    "soic-8"+  ],+  "dependencies": {},+  "hero": {+    "type": "image",+    "path": "docs/hero.png"+  },+  "files": [+    "page.json",+    "README.md",+    "pcf8523.kicad_sym",+    "pcf8523.kicad_mod",+    "pcf8523.glb",+    "pcf8523.step",+    "docs/hero.png",+    "docs/pcf8523-datasheet.pdf",+    "viewers/symbol.html",+    "viewers/footprint.html"+  ],+  "visibility": "public",+  "author": {+    "name": "Ray",+    "email": "[email protected]"+  }+}\ No newline at end of file