Cooling concept

Cooling concept of TO-Leadless and TO-Leaded with gullwing

Comparing TOLL & TOLG Cooling concept of TO-Leadless and TO-Leaded with gullwing

With TOLL/TOLG board mounting, the heat is dissipated through the PCB to the heatsink. Due to the PCB thermal resistance, power losses occur. TOLL is recommended for FR4 and CU-based IMS boards and TOLG is recommended for Al-IMS boards

Cooling concept of TO-Leadless and TO-Leaded top-side cooling

Comparing TOLL and TOLT
Comparing TOLL and TOLT

With top-side cooling setup, the drain pad is exposed on the top of the package allowing the majority of the heat to be dissipated into a top-mounted heatsink. 

This pulls heat away from the PCB resulting in at least 20 percent better RthJA compared to standard over-molded TOLL.