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TPS7H1101A-SP: PSpice WCA Model Guide and Parameters

Daniel Kramnik
Prodigy 10 points
Part Number: TPS7H1101A-SP
Other Parts Discussed in Thread: TPS7H4001-SP,

I did not find the "WCA model guide" referenced in the example worst-case analysis PSpice testbench, I'm wondering if there is one available for this part similar to this: https://www.ti.com/lit/ug/slvuc15/slvuc15.pdf

Also, I notice that the TPS7H4001-SP WCA model includes both a TID and AGING parameter, while the TPS7H1101A-SP WCA model only includes a TID parameter. What does "AGING" model and why was it not needed for this part?

Furthermore, the TPS7H4001-SP WCA model includes tolerances for error amplifier Gm as well as output stage Gm, while the TPS7H1101A-SP WCA model only includes a tolerance for output stage Gm. Is it really not necessary to consider the variation in the error amplifier and its effects on stability?

  • 0
    Prodigy 10 points

    I threw together a random circuit using the TPS7H1101A-SP WCA model and swept the TID parameter from "0" to "100" (units are krad, right?) and found virtually no variation in the modelled small-signal behavior over radiation (less than one tenth of a degree of phase margin difference). Is this the expected behavior? When I sweep from "0" to "100k" I get nonsensical results, so my interpretation is that "0" to "100" is correct. It doesn't seem plausible to me that the part doesn't change at all with radiation exposure and it doesn't make sense to me why a model would be provided instead of just stating that there is no measurable change.

  • 0
    TI__Expert 7085 points

    Hi Daniel,

    Yes there is a User Guide for this model. I am attaching a copy that can be used while we work on making it accessible on the device web page. 

    3022.slvubt7.pdf

    In the TPS7H4001-SP WCA model, the AGING parameter represents measured drift from data taken at 25°C before and after 1,000 hours of testing at 125°C, and is meant to emulate 15 years operating at 65-95°C as defined by Group C specifications in MILPRF-38535.

    The WCA model for the TPS7H1101A-SP does not include an AGING parameter because the frequency response data for this model did not suggest any drift significant enough to be incorporated. For this device, GMea tolerance is incorporated via the tolerance parameters at the end of the device netlist instead of as a more abstracted single GMea parameter. There are not as easily accessible as the GMps and Vref tolerance parameters, but they are there. 

    As for your TID simulations, yes 0-100 is the correct input into the model. The units for that parameter are krad, like you thought. While your results showed strong device performance with little influence from TID, there may be operating conditions and component selections where the influence of TID drift is more noticeable on the frequency response characteristics.

    Thanks,

    Sarah