The RS5C372B is a CMOS type real-time clock which is connected to the CPU via 2-wire and capable of serial transmission of clock and calendar data to the CPU. The RS5C372B can generate various periodic interrupt clock pulses lasting for long period (one month), and alarm interrupt can be made by days of the week, hours, and minutes by two incorporated systems. Since an oscillation circuit is driven at a constant voltage, it undergoes fluctuations of few voltage and consequently offers low current consumption (0.5A at 3V). It also provides an oscillator halt sensing function applicable for data validation at power-on and other occasions and 32kHz clock output (CMOS output) for an external micro computer. The product also incorporates a time trimming circuit that adjusts the clock with higher precision by adjusting any errors in crystal oscillator frequencies based on signals from the CPU. The crystal oscillator may be selected between 32.768kHz or 32.000kHz types. Integrated into an ultra compact and ultra thin 8 pin SSOP package, the RS5C372B is the optimum choice for equipment requiring small sized and low power consuming products. s Features