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UCC3808

Marcello Deluca
Prodigy 40 points

Does someone know how to slow down the soft start of this device? It won't work in a new design we have due to high output capacitance that will cause current limit at start up; we need it slowed to about 50 msec or more for slow ramp up of the duty cycle.

  • 0
    TI__Mastermind 34465 points
    Hi Marcello,
    The UCC3808 is an 8 pin push pull controller that comes without a dedicated soft start pin.
    It has an internal soft start section that is activated when the CS pin exceeds a threshold on the over current comparator.
    You should be seeing a continuous retriggering of this soft start until the over current condition is gone.
    If you want a longer soft start time you can consider slowing down the voltage loop (COMP pin) or disabling the CS pin at startup.

    John Griffin
  • 0 in reply to John Griffin1
    Prodigy 40 points
    Thanks. We tried slowing the COMP pin to no avail. And we don't use the actual CS function - we are using this chip in voltage mode (we feed a portion of the RC pin voltage into CS pin). Can you suggest a different IC that is same as 3808 but w. an easy (programmable) soft start implementation?