The maximum IC junction temperature should be restricted to 125°C under normal operating conditions. Calculate the maximum allowable dissipation, P_D(max), and keep the actual power dissipation less than or equal to P_D(max). The maximum-power-dissipation limit is determined using Equation 15.

Equation 15.

where

• T_A is the maximum ambient temperature for the application.
• R_θJA is the junction-to-ambient thermal resistance given in the Thermal Information table.

The TPS61288 comes in a thermally-enhanced VQFN package. The real junction-to-ambient thermal resistance of the package greatly depends on the PCB type, layout, and thermal pad connection. Using thick PCB copper and soldering the thermal pad to a large ground plate enhance the thermal performance. Using more vias connects the ground plate on the top layer and bottom layer around the IC without solder mask also improves the thermal capability.