RX8900SA Real-Time Clock Modules Epson Timing RX8900SA Real-Time Clock Modules offer a 1.6V to 5.5V timekeeping voltage range and I2C-Bus interface type. RX8900SA modules feature a built-in, frequency-adjusted 32.7kHz crystal unit and DTCXO and multiple functions, including an auto power switch, clock output, wakeup timer, alarm, and temperature sensing. Epson Timing RX8900SA Real-Time Clock Modules operate in a -40°C to +85°C temperature range.