# Real-time Clock/Calendar PCF8563

## Overview
The PCF8563 is a low-power CMOS real-time clock/calendar with programmable features and I2C communication. It’s designed for applications like mobile phones, instruments, and battery-powered devices.

## Features
️· Provides year, month, day, weekday, hours, minutes, and seconds based on a 32.768 kHz quartz crystal.
️· Wide operating supply voltage range: 1.0 to 5.0 V
️· Low backup current: typical 0.25 µA
️· 400 kHz two-wire I2C-bus interface
️· Programmable clock output (32.768 kHz, 1024 Hz, 32 Hz, 1 Hz)
️· Alarm and timer functions
️· Voltage-low detector
️· Integrated oscillator capacitor
️· Internal power-on reset
️· I2C slave address: read A3H; write A2H
️· Open-drain interrupt pin.

## Pin Configuration
️· OSC1: Oscillator input
️· OSCO: Oscillator output
️· INT: Interrupt output (open-drain, active LOW)
️· Vss: Ground
️· SDA: Serial data I/O
️· CLK: Serial clock input
️· CLKOUT: Clock output (open-drain)
️· V DD: Positive supply

## Electrical Characteristics
️· Supply Voltage: 1.0 to 5.5V
️· Supply Current: Varies with CLKOUT state and frequency.
️· Input Voltage: Specified for SDA, SCL, and OSCI.
️· Output Voltage: Specified for CLKOUT and INT.
️· Operating Temperature: -40 to +85°C

## Key Functions
️· RTC: Keeps track of time (seconds, minutes, hours, day, month, year).
️· Alarm: Generates an interrupt when the time matches the set alarm values.
️· Timer: Provides a countdown timer with configurable clock source.
️· Interrupt: Signals events such as alarm, timer completion, or low voltage.

## Communication
️· I2C-bus: Uses a two-wire serial interface for communication.
️· Slave Address: A3H (read) / A2H (write)
️· Data Transfer: 8-bit data bytes transferred via SDA line.

## Additional Features
️· Voltage Detection: Monitors supply voltage.
️· Test Mode: Supports on-board testing.
️· Reset: Internal power-on reset circuit.
️· Registers: Sixteen 8-bit registers for configuration and data storage.