Hello jeffery.huang@sacsys.com.tw,
SOSC has no impact on the LPTMR functionality in VLPS.
The SOSC clock must be disabled before the MCU enters VLPS anyway.
The power manager SDK driver disabled SPLL, SOSC and FIRC and switches to SIRC when the POWER_SYS_SetMode(VLPS, ...) function is called.
Is the SIRC clock enabled in VLPS
Regards,
Daniel