The RX8900CE:UA0 is a compact Real Time Clock (RTC) module that integrates a frequency-adjusted 32.768 kHz Digitally Temperature Compensated Crystal Oscillator (DTCXO). It communicates via a Fast-Mode 400 kHz I2C-Bus interface and supports a wide interface voltage range of 2.5 V to 5.5 V, with timekeeping maintained down to 1.6 V. This 'UA' version provides high frequency stability of ±3.4 ppm over an operating temperature range of -40 °C to +85 °C. Key features include an automatic power switching function for battery backup, alarm and wakeup timer functions, and an integrated temperature sensor, making it ideal for applications requiring precise, low-power timekeeping.