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Original question:

TPS53353: How to evaluate the OVP function of TPS53353?

TPS53353: TPS53353 OVP test

Andy Liu3
Intellectual 2500 points
Part Number: TPS53353

Hi team,

My customer want to know how to test the OVP of TPS53353, in the other E2E answer I see:

"You can forced OV condition on the FB node by using the function generator and pulse it through a diode for ~5us. The set voltage on the function generator is about 20% above the reference voltage (0.6V)."

It means we can add a voltage about 0.72V on FB pin through a diode, if don't have the generator, can we use a DC source to offer 0.72V for FB pin? At the same time, the original feedback loop output goes through the voltage divider resistor to the FB line unchanged.

Best regards,

Andy Liu

  • +1
    TI__Genius 14877 points

    Hi Andy, 

    Using a DC source for the FB pin is okay, but using a diode is recommended so that there isn't any current sinking through to the supply. 

    Best,
    Ryan

  • 0 in reply to Ryan Chen
    TI__Intellectual 2500 points

    Hi Ryan,

    Thanks for your reply, resolved my issue.

    Best regards,

    Andy Liu

  • 0
    TI__Guru 56795 points

     

    When the TPS53353 detects an over-current condition, it will turn on the low-side FET and attempt to discharge the output voltage through the inductor.  If an external voltage source is provided to pull the FB pin up to 0.72V while the output voltage is zero, it can mask some of the fault response and restart aspects due to the external supply holding the FB pin high despite discharging the output voltage.

    If using a DC supply instead of a function generator, it is generally recommended to capacitively couple the DC supply voltage into the FB pin with a 1MΩ or higher bleed resistor so as to induce a short duration OVP pulse rather than hold the FB pin after the OVP response starts.

    For this setup, I would generally recommend:

    1) Set the external supply to provide a voltage of 1V rather than 0.72V.  This will allow the capacitor to charge the FB pin over 0.72V for a period of time while the coupling capacitor is charged.

    2) Select a capacitor that provides a 10μs time-constant with the parallel combination of the feedback resistors

    That should provide a short duration transient of FB above the OVP threshold without holding the FB pin above the OVP threshold once VOUT is discharged.