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TPS54160 - TINA Inverting Application Model and Ripple Noise Reduction

Alex52381
Intellectual 810 points
Other Parts Discussed in Thread: TPS54160, OPA727, TINA-TI, TPS5430, LMR14206

Hello,

I'm looking to design a inverting SMPS to generate -5V from a 5V USB source. The end application is instrumentation, and therefore I must minimize output ripple.

I'm using TINA TI to simulate my design. I have the following questions:

1) Is the TPS54160 transient model sufficent to model my output ripple at steady state? Or is there some other model that I should use?

2) Can I use this model to see the effect of adding an LC output filter for ripple rejection?

3) If I use the transient model as a power supply to my amplifiers in the TINA TI design, will it accuratley model the effects of supply noise? I'm using the OPA727. My assumption is that power supply effects are probably not modeled on all devices, but I don't know how to check that.

Thank you for your guidance,

Alex

  • 0
    TI__Expert 5515 points

    Alex,

    I'm not a power guy, so can't answer #1 & 2 - but someone will.

    For #3, the OPA727 model will indeed show power supply rejection performance. You can tell this by looking at the listing of the macromodel. In TINA-TI, do this by double-clicking on the op amp symbol and then pressing the "Enter Macro" button. There's a feature list in the listing, and PSRR with frequency effects is listed as one of them.

  • 0 in reply to Rick Downs - WEBENCH Design Center
    TI__Guru**** 191445 points

    The TI-Tina model should accurately model the steday staye output voltage ripple providing you have accurately modeled the output filter parasitics.  Yoa can also add an additional LC output filter.  Modeling teh additional switching noise will require that you accurately model the parasitic effects of you PCB layout.  It wil gicve you a good idea, but there is no substisture for building a prototype and taking actual measurements.

  • 0 in reply to JohnTucker
    TI__Prodigy 215 points

    I'm trying to use TINA to simulate an inverting buck-boost based on the TPS54160 but having problems.  I based the simulation on the article: http://focus.ti.com/lit/an/slyt286/slyt286.pdf  and used the matching Excel spreadsheet to determine the component values and circuit modifications.  In the simulation the output voltage won't go below about -2 volts no matter what I do or how I modify the feedback network.

    Do you know if there is already a working TINA circuit I can download that simulates an inverting buck-boost based on the TPS54160 or similar converter?  Or is there a better way to create -5 volts from +12 volts at about 500 mAs.  Thanks for your help.

     

  • 0 in reply to Paul Barker
    TI__Guru**** 191445 points

    IIRC, the models have the GND pins hard coded to "ground".  For teh inverting buck boost circuit, the GND pin must actually be the negative rail, so they need to be assigned as "floating".  There is a model for the TPS5430 that will work in this mode.  I'll have to check with the analog elab to see which models do and do not support inverting buck boost.

  • 0 in reply to JohnTucker
    TI__Guru**** 191445 points

    The TPS54160 Tina model is "supposed" to be set up to allow inverting buck boost config.  It may be possible that you do not have your schematic set up properly.  Can you post it for me to look at?  The other possiblity, is that one of the internal gates is still connected to hard ground.  In that case the model will need to be fixed.

  • 0 in reply to JohnTucker
    Prodigy 40 points

    Hello John,

    I am also planning to use TPS54160 in one of the applications as an inverting buck-boost converter for generating -5 V, 1.5 A supply.

    I tried to simulate this circuit in TINA simulator. As a result, I am seeing steadily dropping negative voltage at the output of the converter, which continues to drop even beyond -5 volts. I also tried to plot the signal on Vsense pin which unexpectedly increases beyond 0.8 volts, which is the internal reference voltage of the regulator.

    I am attaching the TINA circuit schematic .TSC file as well as .JPG snapshot of the diagram window showing upto 2.5 msec of the simulation waveforms which reveal above mentioned problems.

    Any help from your side would be greatly appreciated. Thanks.

    -Mandar T.

     Design Engineer7357.TPS54160.zip

     ifm Engineering Pvt. Ltd., Pune, India

     (www.ifm.com)

  • 0 in reply to Mandar Thite
    TI__Guru**** 191445 points

    According to the analog elab team, that model does not support inverting buck boost.  There are internal nodes tied to ground that cannot be redirected to -Vout.

  • 0 in reply to JohnTucker
    Expert 1985 points

    Hi John,

    I am designing a split rail power supply +/-7V @100mA from 15V supply and plan to simulate this circuit in TINA-TI. So far I have been unsuccessful as the simulation does not run. Can you please suggest how I can simulate this design?

    Regards,

    Shareef

  • 0 in reply to Shareef
    TI__Guru**** 191445 points

    There does not appear to be a model currently available. 

  • 0 in reply to JohnTucker
    Prodigy 100 points

    John,

    Is this true of all TINA macro models for switching DC-DC converter IC's?    Specifically, I am trying to use the transient model for the LMR14206 to simulate a buck-boost converter with a -11V output.   

    I get results similar to those reported by Mandar, with my output voltage being neative, but ramping down beyond the intended contol point.

    Thank you.