There is a diagram in chapter A.5.3 Chip Power-up and Voltage Drops of MC9S12XHY256RMV1.pdf. But I didn't found any where to define this value(Vpora,Vpord). We faced a issue that after stop power supply for 10s around, sometimes mcu can't works correctly. Our assumption is when power supply voltage drops below Vlvrxa and keep decreasing until a value grater than Vpord, both low voltage reset and power on reset are not generated. We have to confirm the Vpord extreme range as this is very important for further projects. Thanks in advance.