OUTLINE
The RS5C321A/B are CMOS type real-time clock ICs which are connected to the CPU via three signal lines and capable of serial transmission of clock and calendar data to the CPU.
The RS5C321A/B can generate 32.768kHz clock pulse controled by register. Driving an oscillation circuit at constant voltage, the circuit presents less fluctuations in frequency and current consumption thank to its minimal voltage fluctuations consequently realizes low current consumption (0.6µA at 3V). It also provides an oscillator halt sensing function for application to data validity at power-on and other occasions. Integrated into an ultra compact and ultra thin 8pin SSOP (0.65mm pitch), the RS5C321A/B are the optimum choice for equipment requiring small size and low power consumption.
The RS5C321A and the RS5C321B reads/writes data at falling and rising edge of serial clock respectively.

FEATURES
• Time keeping voltage 1.6V to 6.0V
• Lowest supply current 0.6µA TYP. (1.5µA MAX.) at 3V
• Connection to the CPU via only three pins: CE, SCLK/SCLK and SIO for addressing and data read/write
• A clock counter (counting hours, minutes, and seconds) and a calendar counter (counting leap years, years, months, days, and days of the week) in BCD code
• 32.768kHz clock pulse controled by register.
• Oscillator halt sensing to judge internal data validity
• Second digit adjustment by ±30 seconds
• 12-hour or 24-hour time display selectable
• Automatic leap year recognition up to the year 2099
• CMOS logic
• Package: 8pin SSOP (0.65mm pitch)