Clock module features low current consumption

The RV-1805-C3 crystal oscillator takes only 17 nA in a calibrated RC mode and 60 nA in crystal mode. The device has an integrated 32.768-kHz quartz crystal, 512 NVRAM, automatic battery switching and charging, and programmable output frequencies from 1/60 to 32,768 Hz. 

This oscillator is targeted at battery-powered applications where low power is important, such as wearables, health/fitness trackers, and commercial products, in the healthcare, automotive, and white goods markets.  It comes in a 3.7 x 2.5 x 0.9-mm package and operates over a temperature range of -40° to +85°C.