公开(公告)号：US20200021244A1

公开(公告)日：2020-01-16

申请号：US16032348

申请日：2018-07-11

Applicant: SILICON LABORATORIES INC.

Inventor： TIAGO MARQUES ,  CHESTER YU

IPC: H03B5/06 ,  H03B5/36 ,  H03L3/00

Abstract: An oscillation circuit including a crystal interface, a crystal amplifier, a level detector, a timing circuit, and a controller. When activated, the crystal amplifier drives a crystal coupled to the crystal interface to establish oscillation, and the level detector indicates when a target amplitude is detected. The controller activates the crystal amplifier and uses the timing circuit and the level detector to measure a startup time of oscillation. The measured startup time is used in calculating a wake up time from a sleep mode in time to perform an operation at a scheduled time. The startup time may be adjusted or averaged and may be remeasured with temperature change. A method of minimizing startup time of a crystal oscillator includes measuring startup time for determining a delay value for programming a wakeup circuit. Robust startup settings may be used in the event of startup failure due to a sleepy crystal.