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TPD6S300: when CC Short-to-VBUS through a cable,during the ringing the maxium voltage can be up to 44V ?How do you get 44V？

user5196705
Prodigy 50 points
Part Number: TPD6S300

  On page 6 of  the  documnet "Circuit protection for your next USB Type-C™ design White Paper  " says ,when CC Short-to-VBUS through a cable,during the ringing the maxium voltage can be up to 44V ?How do you get  44V？ 

  Below is the detailed description，but I still can't  understand that,need your help!!!  

  As the waveform shows, when a cable is present during a short-to-VBUS event, enough inductance exists in the resistor-inductor-capacitor (RLC) circuit relative to the resistance and capacitance to generate a peak voltage during the ringing that is nearly double the value of the settling or final voltage. If the CC line capacitors de-rate greatly over their voltage range, then the peak voltage that is present during the ringing can be more than double the setting or final voltage. This means for a 22-V short, up to 44 V can be seen on the CC or SBU lines during a short-to-VBUS event. What was initially thought to require only 22-V protection ends up needing to be 44 V.

  

Thanks~

  • 0
    TI__Mastermind 28830 points

    Hello,

    This is just the intrinsic properties of any RLC circuit. Any LC circuit has the potential to ring at 2x the applied voltage, and with a low resistance and the parts begin to de-rate as the voltage rises, the ringing can actually go above 2x. What that measurement was showcasing was this fact, and how the part is able to withstand typical ringing caused by the RLC circuit found within the cable itself.

  • 0 in reply to Adam Mc Gaffin
    Prodigy 50 points

    Hi  Adam：

         Thanks for your reply.

         But I  am still confused,could you explain  "LC circuit has the potential to ring at 2x the applied voltage" in detail?

         

        

     

  • 0 in reply to user5196705
    TI__Mastermind 28830 points

    Here is an article you can read that may help. The potential to ring 2x the applied voltage occurs in an underdamped system which is cause by having a small resistance in comparison to the inductance/capacitance. In the article, go to figure 7.6

    Here is another webpage to help explain underdamped and overdamped systems.

    www.nessengr.com/.../