This is a 32KHz crystal oscillator specifically designed for ultra-low power application. The devices are pure 3.3V, so are the power and the output clock. It works in parallel resonant mode of the crystal. When a 32768Hz quartz crystal is connected to pins XIN32K and XOUT32K, the oscillator will output 32768Hz square waves, with the average current less than 2uA.

Process: SMIC 0.18um Logic 1P6M  
Operating voltage range: IS_VCC_XO: 1.62~3.6V  
Operating temperature range: -40~125c  
Operating current: <2uA  
Start time: <200ms  
Drive strength: >INVCLKHD4X_HV cells of SMIC18 library  
Output frequency: 32768Hz (need to select a proper quartz)  
No external capacitor needed