Based on the end application design and operational profile, the I_DD and I_DDIO currents could vary. Systems that exceed the recommended maximum power dissipation in the end product may require additional thermal enhancements. Ambient temperature (T_A) varies with the end application and product design. The critical factor that affects reliability and functionality is T_J, the junction temperature, not the ambient temperature. Hence, care should be taken to keep T_J within the specified limits. T_case should be measured to estimate the operating junction temperature T_J. T_case is normally measured at the center of the package top-side surface. The Semiconductor and IC Package Thermal Metrics Application Report helps to understand the thermal metrics and definitions.