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LMR51450: IBB model

Kei Kuwahara
Expert 6550 points
Part Number: LMR51450
Other Parts Discussed in Thread: LMR33640

Hello team,

My customer wants to simulate inverting buck boost operation for LMR51450.

Is there any IBB model for this device, such as simplis model?

If not, is there any way to simulate IBB operation with PSpice transient model?

Best Regards,
Kei Kuwahara

  • 0
    TI__Genius 14350 points

    Hi Kei,

    The picture below is a 12V to -7.5V schematic made using LM51440. You can refer to this circuit to modify the original pspice model. 

    What's more, you can test it with our EVM. But the following modifications need to be made: The inductor value needs to be recalculated; electrolytic capacitors and ceramic capacitors need to be added between Vin and Vout. When you test, the positive input is connected to Vin, the negative input is connected to Vout; the positive and negative output is connected to the electronic load normally. 

    For some details, you can refer to the ANs below. Thanks.

    6175.Create an Inverting Power Supply Using Peak Current Mode Buck Converter.pdf3513.Working with Inverting Buck_Boost Converters.pdf

    Aurora

  • 0
    TI__Genius 14350 points

    Hi Kei,

    Add the schematic. Thanks.

    Aurora

  • 0 in reply to Aurora Tie
    TI__Expert 6550 points

    Hello Aurora-san,

    Thank you for your quick reply. I have triedthe simulation with the schematics you have given, but it didn't work because the GND level of the simulation is not meant to be used for IBB.

    On the app note : Working With Inverting Buck-Boost Converters, section 4.4.3 states that there is a way to simulate when there is no IBB model, input supply can be connected across the input and output of the DCDC converter. This method seems to be a viable option, but still not working. Is there any example simulation with this configuration?

    Best Regards,
    Kei Kuwahara

  • +1 in reply to Kei Kuwahara
    TI__Genius 14350 points

    Hi Kei,

    It may be that there are limitations in the internal connection methods of our original simulation model, which prevents you from using the pspice model for simulation. We only have individual models that support IBB simulation. 

    You can download the LMR33640 model from the product folder, this includes an IBB schematic that can be simulated. I've provided the zip file here: snvmbv0.zip

    Please follow the AN I sent before to calculate the appropriate value, and then you can modify the test on the EVM. Thanks.

    Aurora