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TINA/Spice/TPS40170: difference between TINA-TI and real maesurement

Hiroshi Sato
Expert 2590 points
Part Number: TPS40170
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Hello,

Our customer evaluating TPS40170 and they have questions.

1. TPS40170 cannot startup, however, due to adding gate resistor 5.6ohm(same value as EVM), it can be fixed.

2. TPS40170 cannot startup, however, due to changing Css from 2.2nF to 47nF, it can be fixed.

(in 1, Css=2.2nF fixed and in 2, no gate resistor attached )

They had use TINA-TI to confirm whether these action is reasonable or not, however, they could not confirm.

Attached TINA-TI circuit(modified from tsc file on the web) can startup without gate resistor, and Css=2.2nF.

Is there any problem for their usage or in macro model ?

Thanks and best regards,

Hiro

TPS40170_TRANS_tset2.TSC

  • 0
    TI__Mastermind 39980 points
    Hello Hiro,

    The TINA model is not going to show the issue.

    Increasing the Css and slowing down the Switch node by adding gate resistor will certainly help if there is noise on the top FET inducing SCP.

    Hope this helps?

    David.
  • 0 in reply to David Baba
    Expert 2590 points

    Hello David-san,

    Thank you for your quick replying and explanation,

    I'll discuss with the customer.

    And, I found that PGOOD rises instead of  Vout had not achieve the set voltage yet. Further I checked, 

    the VFB voltage had start rising before switching. and reached 600mV by a few times switching.

    Is it impossible to accurately simulate VFB behavior with the macro model ?

    Thanks and best regards,

    Hiro