SN65MLVD047A: sn65mlvd047apwr thermal information

Hello,

Thank you for your question. 

Please refer to this application note for further explanation: How to Evaluate Junction Temperature Properly with Thermal Metrics (Rev. B)

Here are snippets of interest:

"RθJC is defined as the thermal resistance between the junction to the case surface (top or bottom), as defined by JEDEC." ...

"The testing method forces almost all of the dissipated heat through the single surface of the device (case top or bottom of package), so RθJC applies to the condition that the chip dissipated power conducts through the single surface of the device package (case top or bottom). This means that the RθJC parameter is generally suitable for the condition that the only heatsinking is attached at the top (or bottom) of the package where more than 90% of the heat is distributed from the top (or bottom), which is very similar to JEDEC test conditions. For a package with bottom thermal pad, the bottom metal pad is allowed to be soldered onto the PCB, but for the RθJC-top parameter, it must be ensured that the top is the main path of heat sinking.

For a SMD device in typical plastic package without top heatsinking, it is incorrect to estimate the junction temperature with RθJC by simply measuring the case top temperature and calculated device power dissipation. This can result in a much higher result than the actual junction temperature. The difficulty of using the RθJC parameter is how to accurately measure the surface temperature of the package attached with the heatsink. The general method is to drill a ≤1 mm diameter through hole in the central portion of the heatsink where it contacts with the chip package. Insert a thin thermocouple wire and well contact with the package surface to measure the case temperature."

Regards, Amy

Hi Harrison,

After doing some research, I believe that the answer here is that the parameter will be RθJC(top). This device does not have a thermal pad. On similar TI devices without thermal pads, the RθJC(bottom) value is not specified. 

I can put in a request form to double check that the RθJC(bottom) value is not specified. The process can take a while (around two weeks). Please let me know if you need a definitive answer on this and I will put the request in. 

Regards, Amy

Hi Harrison,

Thank you for your patience. I have confirmed that since this package does not have an exposed pad, the parameter is referring to RθJC(top). 

Regards, Amy