RX4111CE & RX8111CE Real-Time Clock Modules Epson RX4111CE and RX8111CE Real-Time Clock (RTC) Modules come with a built-in frequency adjusted 32.768kHz crystal unit and battery switch-over function. The RTC modules offer a time-stamp function that logs and stores the real-time and wake-up function to wake up MCU/SoC. These modules feature a 100nA typical low backup current, an auto power switching function, and auto-repeat wakeup timer interruption. The RX4111CE RTC module is designed with an SPI-bus 4-wire interface, whereas the RX8111CE RTC module is designed with an I2C-bus interface with fast-mode 400kHz.