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TPS563257EVM: Thermal resistance clarification

Ramkumar R
Prodigy 20 points
Part Number: TPS563257EVM
Other Parts Discussed in Thread: TPS563257, TPS563252EVM, TPS543320

Tool/software:

Hi Ti,

We planned to use the TPS563257 buck in our design in that the thermal resistance is mentioned as 137.4.

While we calculation the Tj @ 85°C we got 185°C. (Vin is 12V and Iout is =2.5A and V out is 3.3V)

But the as per the datasheet the Tj should be 125°C maximum. 

Can you please confirm whether we use this on our design as our requirement. 

thanks,

Ramkumar.R

  • 0
    TI__Genius 17380 points

    Hi Ramkumar,

    Pls kindly let me check and get back to you next Monday. Thank you!

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    TI__Genius 17380 points

    Hi Ramkumar,

    Pls find more details as shown below:

    (1) The value of RθJA given in this table is only valid for comparison with other packages and can not be used for design purposes. These values were simulated on a standard JEDEC board. These values do not represent the performance obtained in an actual application.

    (2) This RθJA_effective is tested on TPS563252EVM board (2 layer, copper thickness is 2-oz) at VIN = 12 V, VOUT =5 V, IOUT = 3A, TA = 25°C.

    (3) It can work with 12Vin, 3.3Vout/2.5A based on EVM results.

    Thanks!

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    Prodigy 20 points

    Hi Lucia, 

    Thanks for your information.

    If we are going to use this IC at VIN = 12 V, VOUT =3.3V, IOUT = 3A, TA = 85°C condition. what is the Tj ?

    Thanks

    Ramkumar.R

  • 0 in reply to Ramkumar R
    TI__Genius 17380 points

    Hi Ramkumar,

    If your application is 12Vin, 3.3Vout/3A with Ta=85C, I would recommend TPS543320.

    https://webench.ti.com/power-designer/switching-regulator/customize/139?VinMin=12&VinMax=12&O1V=3.3&O1I=3&base_pn=TPS543320&AppType=None&Flavor=None&op_TA=85&origin=pf_panel&lang_chosen=en-US&optfactor=3&Topology=Buck&flavor=None&VoltageOption=None

    You can find more details about Webench simulation results. And the thermal result is based on EVM board.

    Thanks!

    BRs

    Lucia