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TPD6S300: Perform Air ESD testing

Antony Lin
Genius 13480 points
Part Number: TPD6S300
Other Parts Discussed in Thread: , STRIKE

Hi,

With TPD6S300 implemented on a PD type-c port on a laptop, customers tried to perform ESD air 8kV test and see the result in the waveform as below.  You can see the type-c connection is reset at this moment.  Here's some questions ,

  1. Should we expect CCx is disconnected from C_CCx within TPD6S300 when such air ESD is performed?  If so, the reset of the type-c connection should be expected result, right?
  2. After peforming such test several times, customer found the connection is not recovered automatically.  It needs a unplug/re-plug to recover the normal type-c/PD behavior.  How can we explain/debug this?

Thanks!

Antony

CH1_CC1/CH2_CC2/CH3_VBUS

  • 0
    TI__Mastermind 36751 points

    Hi Antony,

    Unfortunately, the expert for this device is out of the office this week. Please expect a reply from him early next week.

    Thank you,
    Eric

  • 0 in reply to Eric Beljaars
    TI__Genius 13480 points

    Hi Eric,

    It become urgent from customer side, can you find someone else to provide some comments firstly?

    The first question we need to clarify is, should we expect a type-c disconnection when we performed an Air-8KV ESD test?

    Below it shows the waveform under the ESD test when the system with TPD6S300 is connected to a PD adapter.  It looks clear that C_CC1 and CC1 is disconnected shortly and recover soon.  Is this expected behavior?  Or we should expect TPD6S300 ESD clamp should be working to handle this ESD and keep the type-c connection during the test?

    CH1:C_CC1  CH2:CC1  CH3:VBUS

    Thanks!

    Antony

  • 0 in reply to Antony Lin
    TI__Genius 9630 points

    Hi Antony,

    In order to prevent the type-c port from disconnecting during an esd strike, please switch from the TPD6S300 to the TPD6S300A. The replacement should be pin to pin identical to the TPD6S300. The A version of the chip prevents disconnect, as seen in the manual:

    Advantages over TPD6S300

    - USB Type-C Port Stays Connected during an IEC 61000-4-2 ESD Strike

    https://www.ti.com/lit/ds/symlink/tpd6s300a.pdf 

    Thanks!

    Emma

  • 0 in reply to Emma Hoying
    Genius 5190 points

    Hi Emma,

     My customer has similar question and they use TPD6S300A. CC voltage is not dropped to 0 but its level is down (for example, from 1.6V to 0.8V) so CC communication is restart. Is this the correct result? 

    Best regards,

    Gary

  • 0 in reply to Gary Teng
    TI__Genius 9630 points

    Hi Gary,

    The CC voltage is expected to change during an ESD strike. This behavior can be seen in the graphs from the TPD6S300A datasheet below. Despite the CC voltage change, the length of time the voltage spikes is so short, that USB Type-C port will remain connected. 

    Section 8.3.5.2 from the TPD6S300A datasheet explains more in depth the chips expected behavior during an ESD strike. 

     

    Thanks,

    Emma

  • 0 in reply to Emma Hoying
    Genius 5190 points

    Hi Emma,

     Please check my customer's test below. CC line drop will cause PD communication lost in some system and their ESD test will be failed. Is there any method to limit the voltage drop? Adding external component / improve PCB design or...?

    Thanks for your kindly help.

    Gary

  • 0 in reply to Gary Teng
    TI__Genius 9630 points

    Gary,

    My first suggestion is to make sure that VBIAS is connected to a 0.1-uF capacitor to gnd. This will assist with ESD discharge. 

    My second suggestion is if your device is connected to a source port. 

    - Short RPD_G2 to C_CC2

    - Short RPD_G1 to C_CC1

    Shorting these to the TPD6S300A CC pins will ensure the dead battery resistors are connected. 

    Section 8.3.5.2 from the TPD6S300A datasheet explains why the dead battery resistors are needed if sourcing. 

    Thanks,

    Emma

  • 0 in reply to Emma Hoying
    Genius 5190 points

    Hi Emma,

     We do all the setting above but the result is the same. So the drop in CC can't be prevent in ESD 8kv test?

    Best regards,

    Gary

  • 0 in reply to Gary Teng
    TI__Genius 9630 points

    Hi Gary,

    Are you using the TPD6S300A on a source port or a sink port?

    During an ESD strike, the CC OVP FET in TPD6S300A will open up and hide the PD controllers RD for 0.93ms, causing a potential for a disconnect on the source USB Type-C port (because the source's minimum disconnect time of 0 ms). Three cases can occur depending on your implementation. 

    1. The TPD6S300A is on the sink and the dead battery resistors are connected.

    The source port will see the TPD6S300A's dead battery resistors, RD, during this time and remain connected. 

    2. The TPD6S300A is on the source. The sink port does not have dead battery resistors. 

    The source port will disconnect because it does not see the sink's dead battery resistors or any Rd. If this is the case for your implementation, you will need to ensure that there are dead battery resistors on your sink port. 

    3. The TPD6S300A is on the source. The sink port has dead battery resistors. 

    The source port will see the dead battery resistors and remain connected. 

    Case 2 may be what is occurring in your system. Ensure that the sink port has dead battery resistors.

    Thanks!

    Emma