LMZ23608: Junction-to-case (bottom) thermal resistance for the LMZ23608TZE/NOPB

Hi,

We will have engineer to look at it.

Okay thank you Neal.

Hello Johanna,

I am double checking the 1C/W number and whether we have more data. I expect to provide you with comments later today.

Cheers,

Denislav

Hi Denislav, That would be great, my analysis is due this afternoon. Here is the link to the data sheet, http://www.ti.com/lit/ds/symlink/lmz23608.pdf

Page 4 on the datasheet lists the thermal resistance numbers for the package for junction-to-ambient 9.9 C/W and junction-to-case (top), 1C/W (so there is no need to verify those numbers). All I need is a reasonable ball park estimate for junction-to-case (bottom), if you are unable to find the exact number. For example, less than 10C/W as a conservative estimate would be good to know. Right now I am using the junction-to-ambient number, 9.9 C/W (which is most likely incorrect) as a placeholder but I suspect that the actual number is much lower than that since the package is thermally enhanced with an exposed pad on bottom. I greatly appreciate your timely responses. Thank you for your help.

Hello Johanna,

I wanted to double check whether the 1C/W junction-to-case(top) is actually to bottom, perhaps there is a mistake in the datasheet. I haven't been able to confirm this yet.

But anyway, internally the chip back is attached to the big exposed pad, similar to a TO-263 package. I think as an estimate, the thermal resistance from junction to bottom will be sub 2C/W. Perhaps using 2C/W as worse case or even 1.5C/W in your analysis will be sufficient. 

I hope this helps for the time being.

I will again try to confirm the 1C/W junction to top spec with the team tomorrow and report back here.

Cheers,

Denislav

Hello Johanna,

I still have not received a confirmation, but most of the team is out this week.

I believe 2C/W is a good conservative number. Once I get a confirmation next week, I will report back with any potential changes. 

Cheers, 

Denislav