• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 2644 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UCC25600: Over Current(Hiccup)

KIM Andy
Expert 2530 points
Part Number: UCC25600
Other Parts Discussed in Thread: UCC28063,

My client configured a 270W power circuit with UCC28063 + UCC25600.

The customer wants to operate the hiccup in over current operation when shorting the output terminal of UCC25600.

However, it seems as if the power is still restarting at soft start as shown below. I want to know if this is the case on the datasheet.

"Once the OC pin voltage becomes less than 0.6 V, the gate driver recovers with a soft start. To enhance"

CH1 : Vss CH2 : Vout CH3 : Voc,  CH4 : Icr

WWTT24.tif

To improve this, we changed the cap of Cp to 1uH and confirmed that it latches.



 

  • 0
    TI__Mastermind 27145 points
    Hi Kim,

    Thanks for your interest in UCC25600. UCC25600 overcurrent wlll cease switching when the voltage on the OC pin exceeds 1V. Once the Voc voltage falls below 0.6V, the device will initiate a soft start sequence and begin switching again. This is slightly different from hiccup current limiting where the soft start sequence is initiated after some delay period.

    From the waveforms you shared, it appears the device initiates the soft start but because the output voltage is still shorted, the overcurrent threshold is exceeded during startup which causes the controller to continuously shutoff and attempt to re-initiate the soft start. This behavior is consistent with the datasheet description.

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    Expert 2530 points
    hi
    Thank you for your quick reply.

    But if OC mode is operating as it is now, is not the excessive current flowing to the FET? It is thought that the FET may be damaged because of it, and the customer is worried about it.

    Best Regards,
    Andy Kim
  • 0 in reply to KIM Andy
    TI__Mastermind 27145 points

    Hi Andy Kim,

    The FET's and rectifying diodes will need to sized appropriately to handle this fault condition. One thing to keep in mind that the FET's will only have to handle this current load momentarily as this is pulsed current.

    Best Regards,

    Ben Lough