PCF8563 Real-Time Clock/Calendar (RTCC)

Overview

The PCF8563 is a CMOS-based Real-Time Clock/Calendar (RTCC) designed for low-power applications requiring accurate timekeeping. It integrates a complete timekeeping solution with a programmable alarm, timer, and interrupt functionality. The device communicates via an I²C-bus interface, making it suitable for embedded systems, consumer electronics, and industrial applications.

With its ultra-low power consumption and wide operating voltage range, the PCF8563 is ideal for battery-powered devices such as smart meters, wearables, and IoT applications. The RTCC maintains timekeeping accuracy with an integrated oscillator circuit that supports an external 32.768 kHz crystal.

Features

• Real-Time Clock/Calendar: Tracks seconds, minutes, hours, day, date, month, year, and weekday.
• Low Power Consumption: Optimized for battery operation with minimal current draw.
• I²C-Bus Interface: Supports standard (100 kHz) and fast (400 kHz) I²C communication modes.
• Programmable Alarm & Timer: Configurable alarm functions and a countdown timer with interrupt capability.
• Oscillator Stop Detection: Monitors oscillator health and flags failures.
• Wide Operating Voltage: Operates from 1.0V to 5.5V, ensuring compatibility with various power supplies.
• Clock Output: Provides a programmable clock output signal (32.768 kHz, 1.024 kHz, 32 Hz, or 1 Hz).
• Small Package Options: Available in SO-8, TSSOP-8, and HVQFN-8 packages.

Applications

The PCF8563 is widely used in applications requiring precise timekeeping and scheduling. Key applications include:

• Consumer Electronics: Smartwatches, digital clocks, and home automation systems.
• Industrial Systems: Data loggers, event timers, and process control equipment.
• IoT & Wearables: Battery-operated sensors, health monitors, and asset trackers.
• Automotive: Dashboard clocks, infotainment systems, and telematics.
• Medical Devices: Portable diagnostic equipment and patient monitoring systems.

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V_DD): -0.5V to +6.0V
• Input Voltage (V_IN): -0.5V to V_DD + 0.5V
• Operating Temperature Range: -40°C to +85°C
• Storage Temperature Range: -60°C to +150°C

Recommended Operating Conditions

• Supply Voltage (V_DD): 1.0V to 5.5V
• I²C-Bus Voltage Levels: Compatible with 1.8V, 3.3V, and 5V logic.
• Clock Frequency (I²C): Up to 400 kHz in Fast Mode.

Power Consumption

• Active Mode (Typical): 0.25 µA at 3.0V, 25°C
• Backup Mode (Battery Operation): < 0.1 µA

Package Information

Available Packages

• SO-8: 8-pin Small Outline Package (150 mil width)
• TSSOP-8: 8-pin Thin Shrink Small Outline Package
• HVQFN-8: 8-pin Thermal-Enhanced Very Thin Quad Flat No-Lead Package

Pin Configuration

• Pin 1 (OSCI): Oscillator input (connects to 32.768 kHz crystal).
• Pin 2 (OSCO): Oscillator output (connects to 32.768 kHz crystal).
• Pin 3 (INT): Interrupt output (open-drain).
• Pin 4 (V_SS): Ground.
• Pin 5 (SDA): I²C data line.
• Pin 6 (SCL): I²C clock line.
• Pin 7 (CLKOUT): Programmable clock output.
• Pin 8 (V_DD): Positive supply voltage.

Functional Description

Timekeeping Registers

The PCF8563 maintains time and date in BCD format across multiple registers:

• Seconds (00-59): Includes a stop bit to disable the clock.
• Minutes (00-59): Stored in BCD format.
• Hours (00-23 or 12-hour AM/PM): Configurable for 24-hour or 12-hour mode.
• Day (01-31), Weekday (0-6), Month (01-12), Year (00-99): Full calendar support.

Alarm & Timer Functions

The device includes:

• Alarm Function: Triggers an interrupt when the set time matches the current time.
• Timer Function: A countdown timer with a resolution of 1/64th second to 255 seconds.

Clock Output

The CLKOUT pin can generate one of four frequencies (32.768 kHz, 1.024 kHz, 32 Hz, or 1 Hz), useful for synchronizing external circuits.

Conclusion

The PCF8563 is a versatile and reliable real-time clock/calendar solution for low-power embedded systems. Its integration of timekeeping, alarms, and timer functions, combined with a simple I²C interface, makes it a preferred choice for designers requiring precision and efficiency in a compact package.