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TPS548D21: Vout tolerance for TPS548D21

Akshat Garg
Intellectual 1040 points
Part Number: TPS548D21

Hi,

Customer is selecting a Vout value which is not available in the table. 

Could you please let me know the equation for calculating the Vout tolerance. 

Both the Vsel and feed back resistor value apart from device reference tolerance will have impact, I could not find the relation. 

Thanks and Regards,

Akshat

  • 0
    TI__Guru**** 191445 points

    Akshat,

    TPS548D21 is designed to use the internal preset voltages.  You can use the external AVSO function to provide an external reference for other voltages.  Since it uses true differential remote sense, there is no direct provision for an external voltage divider.  You can use an external divider from RSP to RSN however.  The initial set point tolerance will be the internal reference tolerance of +/- 0.5 % plus the tolerance variation of your resistor divider network.

  • 0 in reply to JohnTucker
    Prodigy 30 points

    Thanks John,

    I have follow up query related to 

     TPS548d21 Switch node pins connection to Inductor - Current density

    As per the TPS548D21 datasheet, with the Eval board layout, considering Natural convection, below measured temperature data is reported on Pg 9, Figures 3 and 6:

    40A I out, Measured temperature = 86C, Temperature rise at IC = 66C

    30A I out, Measured temperature = 75.3C, temperature rise at IC = 48.3C

     

    So we expect that for 25A load current the temperature rise should be lower than 48.3C..

    In our case we expect the worst case ambient in the vicinity of the TPS548D21 chip to be around 85C

     

    Can an estimate be provided for the temperature rise at IC for two cases?

    1. 20A output load current
    2. 25A output load current.

    Seetaram,

    Yes the power density is quite high.  At 40 A output current you may see temperature rise of 75 deg. C.  At 25 A it should be lower.  Even not considering the copper trace, The IC itself, as well as the output put inductor, will contribute to the temperature rise.  for 25 A output, I would expect the temperature rise to be about 25 deg. C. less or about 50 deg. C.  This is based on measured thermal performance as shown in the datasheet.  Let me know if you have further questions.

  • 0 in reply to seetaram reddy
    TI__Guru**** 191445 points

    Seetaram,

    No need to make multiple posts on the same topic.  Pleas limit to a single thread.