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TCA6416A: TCA6416A ESD tolerance level increasing method

Kazuya Nakai59
Guru 21885 points
Part Number: TCA6416A


 Hello Guys,

 One of our customer is evaluating TCA6416A for ESD tolerance using their own PCB. When they added ESD noise to all outputs of the device, the device was latched up. Once the device is powered off, then the device becomes normal function.

 So could you please tell me how to improve ESD tolerance level of the device?

 Also if you know any stronger device against ESD with same same function, could you please tell me?

 Your reply would be appreciated.

 Best regards,

 Kazuya Nakai. 

  • 0
    TI__Mastermind 24196 points

    Hello Kakai-san,

    Here is an excerpt of the datasheet with the ESD requirements.

    Is the customer trying to meet a specific specification?  Under what test conditions and at what voltage does it "latch up"?  I will look into what we have for higher ESD rated devices in the mean time.

    -Francis Houde

  • 0 in reply to fhoude
    Guru 21885 points
    Hello Francis,

    Thank you for the prompt reply.

    I'm sorry that the failure mode is not latch up. The customer is using TCA6416A with output mode. But when ESD is applied to their board, the output mode is changed to input mode. It seems that the internal registers are intialized. I think some noise goes into VCCI terminal. /RESET termina is pulled up to VCCI near by the device.
    Our customer want to know any 16channel IO expander has stronger tolerant of VCCI noise.

    Could you please tell me such device if you have it?

    Thank you and best regards,
    Kazuya Nakai.
  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 24196 points
    Hello Nakai-san,
    It sounds like the ESD event is causing a POR event. This could be happening by due to ineffective input filtering or even potentially a bad layout that has too much inductance in the ground path. If you want we can take this off line and if the customer is willing I could look at the layout and schematic to see if there is something that can be done. I need more information in order to help. Higher voltage ESD devices will not help this problem, in fact it could make it worse. We need to dampen the ESD even with resistance, minimize inductance, and increase filtering capacitance (assuming put in the correct location).
    -Francis Houde
  • 0 in reply to fhoude
    Guru 21885 points
    Hello Francis,

    I understood what you said well and thank you for your kind proposal to check the layout. I've already checked their board layout and the power line layout for the device is not good. So I will tell them to modify the power line to reduce inductance.

    Thank you again and best regards,
    Kazuya Nakai.