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# CSD19505KTT: CSD19505KTT continuous ID question check

Part Number: CSD19505KTT

Hi Team,

I want to prompt our CSD19505 to my customer, but I want to make some more clear about the Continuous ID specific, can you help me understand. Below is the maximum ratings for continuous, my question is since the Rds,on is about 2.6~2.9mohm, with the 200A continuous IDS, the power loss on MOSFET is about 200x200x2.6mohm=104W!! With the RθJC=0.5W and RθJA=62C/W, how make this be possible? Can you help me understand, thanks a lot!

For my customer, the Vgs is 5V, working temp range will be from -40C to 85C, so I want to know the maximum continuous(If layout is ok) current that our CSD19505 can handle across temp range?

Best regards,

Sulyn Zhang

• Sulyn,
The package limit is a function of the number of bond wires connecting the silicon die to the source post. It is not a thermal limitation. This device actually has the highest package limit of any 3 pin D2PAK in the world because we have increase the number of bond wires - this is really just to make the device more robust.

All the other currents are thermal limitations but they are calculated from specific thermal impedances. How much current the part can handle in your customer's board is determined by your customers junction to ambient thermal impedance. While we can define a junction to case thermal impedance specific to this FET (0.5eg C/W), we cannot predict your customers case to ambient thermal impedance. This depends entirely on the thermal environment (airflow, heatsink, etc...).

Here is a blog I wrote about how these currents are determined: e2e.ti.com/.../understanding-mosfet-data-sheets-part-3

And here is a video that goes into even more detail: training.ti.com/understanding-mosfet-datasheets-current-ratings