The RX8130CE:B3 is a real-time clock module featuring an I²C-Bus interface (Fast-Mode 400 kHz) with a built-in frequency-adjusted 32.768 kHz crystal unit and integrated backup battery charge control function. The module operates with a supply voltage range of 1.25 V to 5.5 V and maintains ultra-low backup current of 300 nA typical at 3 V, enabling extended operation during power loss. It incorporates automatic power switching that monitors VDD voltage and transitions to backup power at 1.2 V minimum, along with reset functions featuring a 60 ms minimum delay and selectable release voltage. The device provides multiple interrupt outputs for alarm events (day, date, hour, minute, second), wakeup timer functionality (244 µs to 7.5 years), and self-monitoring interrupts for crystal oscillation stop and low voltage conditions. Common applications include battery-backed real-time clock systems, IoT devices, industrial controllers, and any embedded system requiring reliable timekeeping with minimal power consumption during backup operation.