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tps563201 simulation parameter

Lucifer
Expert 2600 points
Other Parts Discussed in Thread: TPS563201

Dear Sir,

I am using WEBENCH to simulate TPS563201 for 12V to 5V/3A specification  but it showed that Junction temperature is too high.

Is there any concern about Junction temperature of this application? how can we avoid it? 

Moreover, regarding to the output voltage ripple (2.5mV)  and Phase Margin (60 deg), can we use WEBENCH to simulate it or  generate the result in WEBENCH?

Thanks. 

  • 0
    TI__Expert 4875 points
    Hi,

    I checked Webench and found that it did not directly support 5V output. Could you send me a screenshot for the overtemperature. From my perspective, 5V output is a normal working condition which should not have any worry on the thermal behavior. For the phase margin, Wenbench has this supporting function but it seems like it did not support this part. I will try to contact with the Webench team member to double confirm.

    Best,
    Anthony
  • 0 in reply to Anthony Lang
    Expert 2600 points

    Dear Sir,

    I think that  WEBENCH can’t simulate board side parameter (copper weight, airflow, etc.) so that it can’t be simulated. right? Thanks.

  • 0 in reply to Lucifer
    TI__Expert 4875 points

    Hi,

    I think the Webench is based on the available reference design boards. It does not mean that you cannot use a part if Webench cannot create a design. For the thermal simulation, Webench can run under different copper weight and airflow.

    Best,

    Anthony

  • 0 in reply to Anthony Lang
    TI__Guru**** 191445 points
    Webench does not calculate AC average loop response for DCAP2 devices, so you cannot calculate the phase margin. I got the same over temperature error that you did when I tried to create a 3 A design. Efficiency increases as Vout increases as there is more power delivered to the load. In the ideal world, IC power dissipation should be about constant with varying output voltage. Ramping up the output voltage, I can see two things that are contributing to higher Tj vs output voltage in Webench.

    First, as TPS563201 is not "ideal", the low side FET is about 40% lower RDSon than the high side FET. So as output voltage increases, duty cycle and high side condution time relative to low side conduction also increase. So there is more power dissipated in the IC.

    Second, Webench uses constant inductor value of 2.2 uH. For increased output voltage the p-p ripple current increases and causes higher RMS power dissipation.

    Also, the Theta J-A used to calculate junction temperature from power dissipation looks suspicious.