TPS54225/6 about Thermal information

You should study this document to understand the thermal metrics:

www.ti.com/.../spra953b.pdf

let me know if you have questions about it.

Hi John,

I'm also asked from customer why the Theta-jc is higher than Theta-ja. In the case of TPS54426, Theta-jc is higher than Theta-ja in RGT, but Theta-ja is higher in PWP. I referred app report SPRA953B but I don't find the description that explains the reason of it. Please explain in detail.

Best Regards,
Sonoki

Those numbers are modeled numbers from the packaging group. I'll see if they can explain the difference. It may be some time before I can track it down.

Hi John,

I'd like to listen to the packaging group's view for those number. Please ask them to contact me directly if they need.

sonoki-s@clv.macnica.co.jp


Best Regards,
Sonoki

from the packaging group:

Both of these are exposed pad packages, so the primary heat path is to the PCB through the exposed pad and the solder connection. Very little heat goes out the top of the device.