This RTC IP is specifically designed for low power applications, including a 32768Hz crystal oscillator with embedded analog IOs, an embedded low power LDO and a RTC counter. The power supply is typically 3.3V, but it can be as low as 1.8V while the RTC still functions properly. The oscillator works in parallel resonant mode of the crystal. When a 32768Hz quartz crystal is connected to the pins XIN32K and XOUT32K, the oscillator will output 32768Hz square wave.