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  1. #1
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    Does it really need these ESD components?

    In SmartPhone, there is an ESD components for Display. The display is 4.3 inches touch display.
    The touch display is connected to a modem driver through the ESD component.
    Does The common filter and ESD component protect the modem?
    And another question is: does it really need these ESD components?
    Thank you very much.

    •   Alt5th July 2012, 22:42

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    Re: Does it really need these ESD components?

    Look at this picture: Click image for larger version. 

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    A such ESD test can shot holes in gorilla glass, doubt any protection helps in this case.
    Testing for immunity to electrostatic discharge for cell phones are however done with "only" 8kV.
    A common standard: IEC 61000-4-2
    Anything that the user can touch is tested. Is there for example a USB receptacle is 8kV sparks fired directly on its pins.
    Phone circuit must be protected either with components that react for over-voltage or can high or low-pass filter it as main spark energy is within 1-30 MHz.
    A few other protection methods are to make spark gaps in PCB layout, making plastic cover thicker and partly metallic, air gaps can have over voltage traps, increase isolation for plastic push-buttons with an extra gasket, and touch display can have an ESD coating.
    It is never fun when a phone not pass ESD tests as this kind of test are done very late in the development chain, and if it fail can it require a lot of redesign.


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    •   Alt5th July 2012, 23:54

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  3. #3
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    Re: Does it really need these ESD components?

    Hi, E Kafeman,

    Thank you very much.



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