Hi @ziwu,
I'm sorry for the delay, I'm currently out of office, and I could not reply earlier.
The system clock should be set precisely to one of the clock options listed in the RM, e.g. Table 157. Option A - High Performance mode (CORE_CLK @ 160 MHz).
Then, Bus clock = Register interface clock = AIPS_SLOW_CLK


I currently cannot test the SAF sBoost driver.
But the thresholds are also calculated and set by the MCAL MCU driver if the CMUs are enabled.
Here is an example for S32DS IDE and RTD 6.0.0:
https://community.nxp.com/t5/S32K-Knowledge-Base/Example-S32K344-MCAL-MCU-ClockMonitor-v1-0-S32DS36-...
Regards,
Daniel