CSD18511KCS: thermal resistance Rja test

Hello Johnsin,

Thanks for the inquiry. For the TO220, the Rθja measurement is made in free air as shown in the blog on thermal impedance at the link below. Please review the Application Reports at the other two links below for more information on thermal metrics. Let me know if you have any additional questions.

https://e2e.ti.com/blogs_/b/powerhouse/posts/understanding-mosfet-data-sheets-part-6-thermal-impedance

https://www.ti.com/lit/an/spra953c/spra953c.pdf

https://www.ti.com/lit/an/slua844b/slua844b.pdf

Best Regards,

John Wallace

TI FET Applications