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TPS66020: PD OCP compliance

Part Number: TPS66020

Hi  team,

In PD STP.5, we need VBUS drop to 0.8V in 650ms during OCP,

customer trigger current limit at 3.5A, but as you can see , it drop a bit but then bounce back to 5V for a while and eventually drop to 0. 

but the total time is over 650ms.

May I know why did it bounce back  with current is already 0A

while is current , green is VBUS.

  • Hello,

    The voltage will be impacted by the load.  If the load is removed (current goes to 0A) then the voltage will return to 5V. 

    Regards,

    Chris

  • Hi Chris,

    but why did VBUS drop to zero eventually if load is 0A for a while?

    their E-load was in Constant current mode and  theoretically  our IC triggered current limit at 3.5A should keep at 3.5A until it thermal shut down and turn off PP5V , right?

    but why and how did the current shown zero here? and what's more VBUS drop eventually even there's no current for a while?

     

  • Hello,

    but why did VBUS drop to zero eventually if load is 0A for a while?

    This is not clear.  Is there any interaction between the TPS66020 and the PD controller where the PD controller turns off PPV5 via EN0/EN1 in the event of a fault (/FLT)?

    their E-load was in Constant current mode and  theoretically  our IC triggered current limit at 3.5A should keep at 3.5A until it thermal shut down and turn off PP5V , right?

    Correct.

    but why and how did the current shown zero here? and what's more VBUS drop eventually even there's no current for a while?

    Can you confirm the states of the TPS66020?  Does the device leave SRC 3.0A and go to SRC FAULT and then return to SRC 3.0A when the fault is removed and then finally end in the disable state when EN1_EN0=00b or 01b?

    Regards,

    Chris