R2262 Series

3-wire Serial Interface Real Time Clock (RTC) with Battery Backup Switch-over Function

The R2262 is a CMOS real-time clock IC connected to the CPU by three signal lines, CE, SCLK, SIO, and configured to perform serial transmission of time and calendar data to the CPU. Further, battery backup switchover circuit and a voltage detector are incorporated for secondary battery. The periodic interrupt circuit is configured to generate interrupt signals with six selectable interrupts ranging from 0.5 seconds to 1 month. The 2 alarm interrupt circuits generate interrupt signals at preset times. As the oscillation circuit is driven under constant voltage, fluctuation of the oscillator frequency due to supply voltage is small, and the time keeping current is small (Typ. 0.30 µA at 3V). The oscillation halt sensing circuit can be used to judge the validity of internal data in such events as power-on; the supply voltage monitoring circuit is configured to record a drop in supply voltage below supply voltage monitoring threshold setting. The 32.768 kHz clock output function (CMOS output) is intended to output sub-clock pulses for the external microcomputer. The oscillation adjustment circuit is intended to adjust time counts with high precision by correcting deviations in the oscillation frequency of the crystal oscillator. Battery backup switchover function is the automatic switchover circuit between a main power supply and a backup battery of secondary battery. Since the package for this IC is TSSOP10G or QFN0202-18, high density mounting of ICs on boards is possible.