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UCC28950: UCC28950 COMP pin questions

Red Yen
Expert 4360 points
Part Number: UCC28950

Hi Team 

in normal operation mode, what happened if pull down COMP pin suddenly, would IC be damaged or just caused the controller shutdown ?

if do this test for a long period, any side effect?

thanks a lot 

  • 0
    TI__Mastermind 25570 points

    Hi Red

    It's not advisable to pull COMP down (or up) externally. If you want to stop the UCC28950 from running then the correct option is to pull the SS/EN pin down using a small MOSFET or Bipolar transistor. <500mV is typically enough for shutdown.

    Regards

    Colin

  • 0 in reply to Colin Gillmor
    TI__Expert 4360 points
    thanks, Colin,

    I am just curious any side effect something like damage IC or outside circuit if pull COMP low externally?
    the question behind is not for protection

    thanks a lot
  • 0 in reply to Red Yen
    TI__Mastermind 25570 points

    Hi red

    Just to summarise this thread. The normal configuration for CI/CV control using an external error amplifier is to configure the error amplifier on the UCC28950 as a unity gain follower and to use the EA+ as the control input – the sketch below is an analog implementation of this idea.

    This implementation also means that the control input signal does not have to overcome the output drive capacity of the COMP pin.

    It should be ok to drive the COMP pin directly providing that the load on VREF is 23mA less the 8mA (worst case) used internally by the error amp  – so the customer could put an additional 15mA ext load on VREF.  The customer should evaluate this option carefully if they wish to use it.

    Regards

    Colin