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TPS62110 TINA-TI Model Does Not Work in Inverting Configuration? Or Will the Part Not Work?

Andrew Gibson
Intellectual 640 points
Other Parts Discussed in Thread: TPS62110, TINA-TI, TPS62000-HT

Hi - I have been trying to use TINA-TI to simulate and evaluate an inverting DC-DC circuit, "borrowed" from the MC34063 datasheet.  In case the ground side power MOSFET in the TPS62110 was not working properly I added a diode in parallel but have seen identical simulated results either way - the output Voltage never gets below 0.  In addition, if an initial condition negative output Voltage is applied to a filter capacitor it rapidly floats up to 0 and stays there.  I can see that current is being pulled up from ground through the inductor though.

Are there grounded points in the (locked, proprietary) TPS62110 model that will mess up this style of inverter i.e. where the TPS62110 ground pins are floating on a capacitor to ground?  Or is there something about the real IC that will prevent it from being used this way?

For what it is worth I have just downloaded SLVA317B to check it for clues but very much welcome your thoughts to see if this is a model problem or a real problem. 

Thank you in advance.

  • 0
    TI__Guru**** 191445 points

    For the inverting buck boost topology to work, the IC GND node becomes -VOUT.  It is likely that some internal GND nodes are hard connected to GND so that a negative output voltage cannot be realized.  I'll move your post to the models forum so they can verify, but this is the case with other models I have used.

  • 0 in reply to JohnTucker
    Intellectual 640 points

    Hi John - thank you.  To confirm, with proper electrical connections the actual circuit may/should work but the simulation will not?

  • 0 in reply to Andrew Gibson
    TI__Guru**** 191445 points

    I have not tried the TPS62110 as inverting buck boost (that device is not one that I directly support, so I have not used it before).  I can only comment that I have seen similar issues with TINA_TI models for parts that I do support.  Internla nodes were tied to GND that needed to "float" so they could be tied externally to GND for buck operation or to - VOUT for inverting buck boost operation.  I'll ask my contact in that group about it.  I am surprised he has not already posted as he is usually very quick to respond.

  • 0 in reply to JohnTucker
    TI__Mastermind 39210 points

    Hi Andrew,

    In most of our models, we connect the GND pin to node 0, so it can not be used in the inverting configuration. We only test the inverting configuration if we are told to do so at the time of model development.

    Best regards,

    Nikhil

  • 0 in reply to Nikhil Gupta (Product Folder Models)
    Intellectual 640 points

    Hi Nikhil,

    If you are developing a model for the TPS62000-HT please set it up so it can be simulated in the inverting configuration.

    Is it possible for you to upgrade the TPS62110 model to allow the inverting configuration? 

    Thank you for your consideration.

    Andrew