2/3-Wire Interface Real-Time Clock ICs Nisshinbo 2- and 3-Wire Interface Real-Time Clock (RTC) ICs perform serial transmission of time and calendar data to a CPU. The R2061 (3-wire interface) RTC is connected to the CPU by CE, SCLK, and SIO signal lines. R2061 includes a battery backup switchover circuit and a voltage detector. This Nisshinbo IC features 0.75V minimum supply voltage and 0.4µA low power consumption. The R2061 device also includes a periodic interrupt circuit that is configured to generate interrupt signals with six selectable interrupts ranging from 0.5 seconds to one month. The two-alarm interrupt circuits generate interrupt signals at preset times.