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UCC2817: Do we need soft start cct for UCC2817?

Andrew Massey
Prodigy 150 points
Part Number: UCC2817

Hi,

There is a TI.com app note detailing a soft start cct for UCC2817....what happens if we dont implement this.....?....surely the OVP pin will work, and surely the IPKLIM pin will work?....why do we need this extra soft start cct?

www.ti.com/.../slua321.pdf

  • 0
    TI__Mastermind 24245 points

    Hi Andrew,

    Thank you for your query on UCC2817.

    The SS pin capacitor should provide the required softstart time, to ramp the duty cycle slowly preventing overshoots. OVP and PKLMT will work, but the purpose of SS is to prevent the system from triggerng protection just after brown out/line drop situations because the duty will be maxed out. I would suggest designing without the external softstart initially and add this incase the system trips hitting PKLMT current (which in turn would gradually ncrease the peak current at startup).

    Regards,

    Harish