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LM5156H: How can I tune Overload Current In flyback topology?

Aditya Yedur
Prodigy 130 points
Part Number: LM5156H
Other Parts Discussed in Thread: LM5156, LM51561

Hello All

I am developing isolated DC to DC For as per below specs.

Input - 17 VDC to 32V DC.

Output - 5 VDC 

Load - 3A.

Overload current - 3.5A 

using which pin of the IC Can I tune Overload current protection?

Please explain working for the same.

Regards

Aditya Yedur

  • 0
    TI__Mastermind 19540 points

    Hi Aditya,

    Thanks for using the e2e forum.
    LM5156x in isolated flyback topology can be used for this application.

    There are two version of the device:
    LM5156: cycle by cycle current protection
    LM51561: cycle by cycle current protection AND hiccup mode protection

    Cycle by cycle current protection:
    Once the device senses an overcurrent at the CS pin, the gate will be turned off for the rest of the switching cycle. This can be triggered every cycle, leading to a continuous operation with reduced duty cycle.

    hiccup mode protection:
    this feature is only active in the LM51561 option.
    If the device senses 64 cycles of continuous OCP trigger, the device will go into a hiccup state, where the gate is turned for a longer period of time. Afterwards the device will try to restart in softstart mode.

    Both features are described in more detail in the according datasheet.

    Please let me know if there are additional questions.
    Best regards,
    Niklas