The SM8580A is a real-time clock IC based on a 32.768kHz crystal oscillator, which features a 4-bit parallel interface for communication with an external microcontroller. It comprises second-counter to year-counter clock and calendar circuits that feature automatic leap-year adjustment up to year 2099, alarm and timer interrupt functions, clock counter change detect functions, ±30-second correction function, time error correction function, and built-in temperature sensor. The 4-bit parallel interface is compatible with general-purpose SRAM over a high-speed bus.