__HAL_PWR_UNDERDRIVE_ENABLE macro

This mode is enabled only with STOP low power mode. In this mode, the 1.2V domain is preserved in reduced leakage mode. This mode is only available when the main regulator or the low power regulator is in low voltage mode. If the Under-drive mode was enabled, it is automatically disabled after exiting Stop mode. When the voltage regulator operates in Under-drive mode, an additional startup delay is induced when waking up from Stop mode.