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UCC28180: UCC28180 PSpice simulation problem

Part Number: UCC28180

Hi,

I'm running the PSpice model in file SLUM423.ZIP provided for UCC28180. I would like to know what is the value of default voltage - 162V referring to? Based on the design calculator provided in excel file SLUC506, i guess this 162V is the conversion value from RMS input voltage to average voltage, but not sure which value is this referring to. 

Also, I'm quite new with pspice, i need some guidance on the simulation profile as the default simulation profile is run under AC Swipe/Noise. When i edit the simulation profile to time domain, and set the run time to 1000ms, i observed that the Vload is decreasing (not 390V). 

And same goes for the output current. 

Kindly advice, thank you. 

Baz

  • Hello Baz, 

    The 162V dc source represents the peak of 115Vrms AC line voltage.  It is basically an arbitrary voltage as a starting point for analysis. 
    DC is used to speed up simulation. 
    You can change it to any (reasonable) value you want, typically in the range of 100V to 375V, to assess the frequency response variations across line voltage.

    I believe the change to time domain doesn't work because there is huge inductor in series with the feedback network.   This inductor ( and huge cap) is used to inject the AC sweep signal into the feedback, but I believe that it interferes with normal transient operation.  
    I suggest to disconnect the L and C from the feedback and connect Vout directly to the 49.9R resistor.  Then run the transient analysis.  

    I would have tried this myself to be sure, but when I opened my PSpice program, it informed me there was an update available so I loaded that.  Now that it is loaded, I can't get my PSpice to start.  I think I'll have to remove everything and reload PSpice from the TI.com site. 

    Regards,

    Ulrich

  • Hi Ulrich,

    Thank you so much. it's work now. 

    Regards,

    Baz