Hi Naoki san,
Startup time is a measurement of the time it takes for the ECO to stabilize at the desired frequency after it is enabled. This value will vary with both hardware and firmware configuration. Maximum values for these specs are shown in the PSoC 3 and 5LP device datasheets.
Please check the clock startup function “ClockSetup()” in the cyfitter_cfg.c source file that is automatically generated by PSoC Creator. There is a time out and provision to call the callback function. The code will also get stuck in while loop in such a situation. You can also add a custom code to decide what to do when such an error happens. cyfitter_cfg.c can be referred for more details.
Thank you for the answer. This question has been resolved.