This Real Time Clock (RTC) is a low-power, full Binary-Coded Decimal (BCD) clock/calendar that also features 56 bytes of non-volatile SRAM. Data communication is handled by a bidirectional I²C serial interface. The data supplied by the clock function includes seconds, minutes, hours, day, date, month and year. The device also has automatic month-end adjustments for non-31 day months and for leap years. The clock will operate in 12- or 24-hour format and has an AM/PM indicator. This RTC has built-in power-sense circuitry that detects power failures and automatically switches to a backup supply, keeping timekeeping functions active.

• 0°C to +70°C Commercial temperature range
• Surface mounting SO-8 package
• 56 byte Battery-backed NV SRAM for data storage
• I²C Serial interface
• Programmable square-wave output signal
• Automatic power-fail detect and switchover circuitry
• Consumes <500nA in battery-backup mode with oscillator running

The SNAPHAT is a snap-on package containing a crystal and a lithium coin cell and is designed to snap onto the ST TIMEKEEPER IC after the high temperature surface-mount solder process.

• Clock frequency 32.768kHz
• Frequency precision 35ppm
• Supply voltage 2.8V