ILO Crystal Trimming and Initializing

Question: How is the ILO trim initialized and what is the range of the trim

 

Answer:

The ILO trim is initialized to be in the center so that it is as close to 32KHz as possible. This initialzation does not take place in the boot code. The initial value is loaded into the register in the factory. The trim range can be anywhere between less than 10KHz to 110KHz. The step size is non-linear and ranges from approx 7KHz to 14KHx. The sleep oscillator is not designed for accurate operation. Its purpose is to wake up from sleep. Therefore, the oscillator design is restricted by the current in sleep which is about 1uA.