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TPS7A54-Q1: Average modelling

Prodigy 60 points

Replies: 1

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Part Number: TPS7A54-Q1

Hi

I am trying to do Average modelling for the IC, Looking at the parameters in the datasheet, I was able to find Line and Load Regulation data from which, I could approximate open loop Output resistance, from Line regulation = Rol/1+Aol*Beta and Load Regulation = 1/Aol*Beta; But it leaves much to be desired in order to find the stability of the system. Let me know what other data i could extract from the datasheet to perform AC anaysis of the circuit. Also, let me know if there is any specific models available (i was able to just find Transient SPICE file on the web).

Regards

Ravi

  • Hi Ravi,

    The transient SPICE file provides a good steady state model of this component.
    It will be challenging to build a model that accurately reflects the AC performance from the datasheet.
    There are multiple feedback loops inside modern linear regulators which all must be modeled properly.
    The data to replicate these loops is not in the datasheet.

    Our recommendation is to use the datasheet values for Cin and Cout to meet the definition of stability.
    You can obtain an evaluation board for this LDO (part number TPS7A54EVM-006) and add your specific input and output capacitors.
    A load transient can then be performed and the phase margin can be estimated by the number of rings in the transient response.
    See the following App note which discusses this:

    www.ti.com/.../slva381b.pdf

    Thanks,

    - Stephen

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