Implementation of power converter modules with low-profile and fine-pitch such as MircoSiP packages typically requires special attention to power dissipation and thermal rise. Many system-dependent issues such as thermal coupling, airflow, added heat sinks and convection surfaces, and the presence of other heat-generating components affect the power-dissipation limits of a given component.

The TPSM82903 is designed for a maximum operating junction temperature (T_J) of 125°C. Therefore, the maximum output power is limited by the power losses that can be dissipated over the actual thermal resistance, given by the package and the surrounding PCB structures. If the thermal resistance of the package is given, the size of the surrounding copper area and a proper thermal connection of the module can reduce the thermal resistance. To get an improved thermal behavior, TI recommends to follow the following guidelines:

• Use a multi-layer PCB boards (at least four layers, with 1-oz or more copper).
• Use thermal vias on the GND pin to connect the GND top layer with the GND inner and bottom layers. This helps dissipate the heat across layers.
• Generate as large a GND plane as allowable on the top and bottom layers, especially right near the package. The exposed thermal pad of the device sits right at the middle of the package. This is ideal for thermal dissipation. To take advantage of that, TI recommends the ground plan to cross through the package to allow maximum ground plan connection with the exposed pad. See Figure 8-61 how the north ground pour is connecting with the south ground pour as it crosses through the exposed pad of the package.
• Use thermal vias on the VIN and VOUT pins (as close as possible to the pin) and around input and output capacitors to connect the VIN and VOUT top layer with the inner and bottom layers. This helps dissipate the heat across layers as well as decreases the resistance drop on these traces.
• Use wide and short traces for the main current paths to reduce the parasitic inductance and resistance and helps on thermal dissipation.
• Introduce airflow in the system if possible.
• Refer to Figure 8-61 for an example of component placement, routing and thermal design.

For more details on how to use the thermal parameters, see the Thermal Characteristics of Linear and Logic Packages Using JEDEC PCB Designs and Semiconductor and IC Package Thermal Metrics application reports.

If short circuit or overload conditions are present, the device is protected by limiting internal power dissipation.

The device is qualified for long term qualification with a 125°C junction temperature.