Designing with GaN switches – app note explores thermal aspects

December 17, 2014 // By Graham Prophet
GaN Systems has an Application Note on designing with Gallium Nitride enhancement mode power switching transistors, specifically related to devices occupying its proprietary GaNPX packaging.

GaN Systems' (Ottawa, Canada) Application Note for design engineers sets out thermal design guidelines and PCB layout choices for its enhancement mode power switching transistors, which are supplied in its own GaNPX device packaging. These are the first discrete power devices to be embedded in a laminate construction - conventional packaging techniques, such as clips, wire bonds, and moulding compounds have been replaced with galvanic processes. These advanced design features of GaNPX packaging are claimed to significantly increase the current carrying capability of GaN Systems’ devices and significantly reduce critical loop inductance, simplifying driving the high speed, high current switches.

The Application Note gives a thermal analysis of GaN Systems’ GS66508P E-mode GaN, 34A, 41 mΩ power switch, together with diagrams showing its thermal dissipation paths and further explanation of how heat is dissipated by the packaging design. The second part of the Application Note looks at the key PCB factors to consider when designing with GaNPX devices: the heat spreading copper pad and the design of the thermal vias. The third section contains a thermal analysis of three different PCB layouts with different copper layers and thicknesses and looks at details of the optimum layout. Lastly, there is a section looking at how designers can utilise the maximum power capability of GaN Systems’ devices and estimate the maximum power capacity of the system they are designing.

GaN Systems;