DLPC3479: What is the Junction-to-board thermal resistance of DLPC3479

Hello Sayak, 

The DLPC3479 datasheet does not include a junction-to-board (θJB) value because this parameter is not a fixed property of the device and depends on the specific PCB layout. The junction-to-board (θJB) parameter depends heavily on the actual PCB design, including factors such as copper plane size, number of thermal vias, etc., which determines how heat is transferred onto the board. Since these conditions vary from one design to another, TI does not provide a fixed θJB value.

Calculate θJB must be determined either through thermal simulation of your board design (using the published θJC value as an input) or through direct measurement on hardware by applying a known power load and comparing junction temperature to board temperature. The DLPC3479 datasheet provides a junction-to-case thermal resistance of 10.1 °C/W and a junction-to-ambient thermal resistance of 28.8 °C/W in still air. 

For accurate thermal analysis, the best approach is to use the published θJC value in the DLPC3479 datasheet in combination with your own board-level thermal model or simulation, which will give results specific to your design. Please refer to Section 6.3 (Recommended Operating Conditions), Section 6.4 (Thermal Information), and Section 10.1.9 (Thermal Considerations) of the DLPC3479 datasheet for more information regarding thermal resistance on the DLPC3479 controller.  

Regards, 

Tristan Bottone