1. What is the maximum reaction time Trr of the reset ?
overvoltage is the maximum reaction time 83uS;
2. What is the maximum voltage drop that can occur during Trr max ?(indicated by delta U in the picture)
It depends on output capacitor and loads after regulators.
3.What is the minimum threshold voltage Vrt, which triggers a reset from the reset circuitry? (indicated by Vrt min in the picture)
If UV configured as RSTB impacted, it is min UV threshold that can be found in the datasheet
4. What is the minimum voltage Vdd, which ensures the ECU does not reset?
it corresponding to the max UV threshold that can be found in the datasheet.