CSD18540Q5B: Thermal Characteristic of MOS

user6360875

Part Number: CSD18540Q5B

hi TI member

From the datasheet of MOS , we can find the thermal information :

About RθJC --Junction-to-case thermal resistance ， how to define the case thermal , top case or the bottom case of the MOS ？？？

when check some MOS from Infineon, you can find two RθJC , one is bottom case , one is top case

'cause I don't know the internal structure of TI MOS， when adding heatsink , which side should install , from the Top side of the MOS ,or the Bottom side ?

thanks

over 2 years ago

+1 John Wallace1 over 2 years ago

TI__Mastermind 36770 points

Hello Robin,

Thanks for the inquiry. RθJC specified in the CSD18540Q5B datasheet is to the large thermal pad (drain) on the bottom of the package. RθJC(top) is not specified but is estimated by simulations to be about 8°C/W. The primary path to remove heat from this 5x6mm SON package is thru the thermal pad and into the PCB using thermal vias in the pad to spread the heat to the inner and bottom layers. Top side cooling can be done with a heatsink but its effectiveness will be limited by the thermal resistance thru the top of the plastic package. For more information on how TI tests and specs thermal impedance, please see the blog at the link below.

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

Best Regards,

John Wallace

TI FET Applications

0 user6360875 over 2 years ago in reply to John Wallace1

Intellectual 280 points

Thanks John

I have know it well

Power management

Power management forum

CSD18540Q5B: Thermal Characteristic of MOS