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TPS543C20A: waht will be damaged or wrong when Iout > 40A operation

Kazuhiko Hirano
Genius 14918 points
Part Number: TPS543C20A
Other Parts Discussed in Thread: TPS543C20

Hello,

 

My customer is designing POL for a CPU using TPS543C20A.

Vin = 12V , Vout =0.83V and Iout max was supposed to be 40A.

However, the CPU seems to consume more than 40A, 42~43A.

 

By adjusting ILIM larger, TPS543C20A looks working somehow with Iout=42~43A now.

There is a lot of airflow to cool TPS543C20A down on their PCB and thermal shutdown does not occur.

 

I told that TI can not guarantee >40A continuous Iout at TPS543C20.

 

However, my customer would know what exactly go wrong at TPS543C20 when Iout >40A.

Please let me know how I should respond.

 

Best regards,

 

K.Hirano

  • 0
    TI__Genius 17905 points

    Hirano-san,

    In addition to temperature, the concern with going to higher output currents would be exceeding the safe operating areas of the power FETs. I would recommend that the customer measure the HS FET Vds (VIN to SW) and LS FET Vds (SW to PGND) with a differential probe close to the IC pins, to check that these measurements are not exceeding the <10ns max ratings listed in the datasheet.

  • 0 in reply to Kris F
    TI__Genius 14918 points

    Kris,

     

    Thank you for your response.

     

    Do you mean HS FET Vds and LS FET Vds could exceed 20V less than 10ns?

    As far as tj <125oC and both HS FET Vds and LS FET Vds do not exceed 20V more than 10ns, TPS543C20 can drive >40A Iout with no damage?

     

    Best regards,

     

    K.Hirano

  • 0 in reply to Kazuhiko Hirano
    TI__Genius 17905 points

    Hirano-san,

    Yes, if junction temperature is not exceeding 125C and the VDS is not exceeding the datasheet limits, then I would not expect damage when operating a little above 40A output.

    Keep in mind however that when we validated this device during its development, we focused on testing operation only up to 40A steady state output current.

    Regards,
    Kris