For a DC/DC module 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 TPSM8D7x20 module is available in a small package to cover a range of application requirements. The Thermal Information table summarizes the thermal metrics of this package with related detail provided by the Semiconductor and IC Package Thermal Metrics application note.

The 112-pin BGA package offers a means of removing heat through the BGA balls. This design allows a significant improvement in heat sinking. Designing the PCB with thermal lands, thermal vias, and one or more grounded planes is imperative to complete the heat removal subsystem. The exposed pads of the TPSM8D7x20 are soldered to the ground-connected copper lands on the PCB directly underneath the device package, reducing the thermal resistance to a very low value.

The TPSM8D7x20 uses an overmolded package construction which can be interfaced to a heat sink or cold plate for better thermal dissipation. This is an effective method of increasing the thermal SOA of the device and allow for less derating of the output current due to thermal limitations.

Preferably, use a six-layer board with at least 1oz copper thickness for all layers to provide low impedance, proper shielding and lower thermal resistance. Numerous vias connected from the thermal lands to the internal and solder-side ground planes are vital to promote heat transfer. In a multilayer PCB stack-up, a solid ground plane is typically placed on the PCB layer below the power-stage components. Not only does this design provide a plane for the power-stage currents to flow, but the design also represents a thermally conductive path away from the heat-generating device.