RX-8571SA/LC Real-Time Clock Modules Epson Timing RX-8571SA/LC Real-Time Clock Modules offer a 1.6V to 5.5V operating voltage range and 220nA typical backup current. RX-8571SA/LA modules feature a built-in frequency adjusted 32.7kHz crystal unit, I2C-Bus interface, and 128-bit user RAM. These modules have numerous functions, including timers, alarms, and full calendar. Epson Timing RX-8571SA/LC Real-Time Clock Modules operate in the -40°C to +85°C temperature range.