8.2.2.5 Thermal Considerations

The useful range of a driver is greatly affected by the drive power requirements of the load and the thermal characteristics of the package. In order for a gate driver to be useful over a particular temperature range, the package must allow for the efficient removal of the heat produced while keeping the junction temperature within rated limits. The thermal metrics for the driver package is summarized in the Thermal Information of the datasheet. The θ_JA metric must be used for comparison of power dissipation between different packages. The ψ_JT and ψ_JB metrics must be used when estimating the die temperature during actual application measurements. For detailed information regarding the thermal information table, please see the Application Note from Texas Instruments entitled, Semiconductor and IC Package Thermal Metrics IC Package Thermal Metrics (SPRA953).

The UCC27611 device includes a 6-pin DRV package with exposed thermal pad. The exposed thermal pad in DRV package provides designers with an ability to create an excellent heat removal sub-system from the vicinity of the device, thus helping to maintain a lower junction temperature. This pad must be soldered to the copper on the printed circuit board directly underneath the device package. Then a printed circuit-board designed with thermal lands and thermal vias completes a very efficient heat removal subsystem. In such a design, the heat is extracted from the semiconductor junction through the thermal pad, which is then efficiently conducted away from the location of the device on the PCB through the thermal network. This helps to maintain a lower board temperature near the vicinity of the device leading to an overall lower device junction temperature.