Achieving the best thermal performance is an important aspect of the PCB layout for DC/DC converters.
This is especially important for applications with high ambient temperatures which causes tough thermal
requirements. End equipment's that often have these thermal challenges are active antenna systems
(AAS), remote radio units (RRU), base band units (BBU), data center switches, metro data center
interconnects, and broadband fixed line access. This application note examines how different layouts
affect the thermal performance of the TPS54424 and TPS54824 converters. These converters use the
HotRod™ QFN package for high power density and to minimize the parasitic resistance and inductance of
the package. However, a difference with this package compared to a standard QFN is there not a large
thermal pad on the bottom of the package. This raises the question on how to get the best thermal
performance from the HotRod QFN package. Layout factors evaluated in this application note are thermal
via placement, thermal via rules, and copper area.