A micro-power MEMS-based Temperature Compensated Oscillator (TCXO) supports Sleep Clock Accuracy (SCA) of less than 5 ppm across the device operating temperature range of -40°C to 85°C. Under the same operating conditions, the equivalent quartz crystal solution can only support an SCA greater than 200 ppm. The configured SCA values must match the actual frequency stability of the sleep clock used in the wearable.  Failure to do so may cause the BLE link to time-out. A 32kHz 5ppm TCXO breaks the quartz sleep time barrier of 8 s, maximizing the device power savings potential.