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TINA/Spice/UC2842: UC2842 in UVLO mode all the time and restarting

Sowmya Akella66
Intellectual 395 points
Part Number: UC2842
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Hi,

I am trying to simulate UC2842 for a universal Input AC supply.

I am currently using the reference schematic provided in the UC x842 datasheet as it is (Fig 25).

I am observing that everytime the IC tries to startup, voltage on the VCC pin( Vref in my simulation) goes past 10V and then as it touches 16V, it restarts again.

I have attached the waveform.

I see that a very high current is going into the device Vcc pin for some reason on startup. Could this be a reason? And how can I prevent this?

Can I get some help on why this is happening? 

  • 0
    TI__Expert 7395 points
    Sowmya,

    Thanks for your interest in TI here.

    For completeness can you share an image of your schematic as well as the simulation conditions you are running?

    Are you implementing soft start using RSS and CSS? If so maybe try increasing the time constant still further to see if it improves?

    Regards
    John