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    seseandy
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    How to select I/O pad ,please give some guidelines

    thanks!

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    Re: How to select I/O pad ,please give some guidelines

    1.System Speed(CLK)
    2.In/Out/Inout
    3.pull high/pull low



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    Re: How to select I/O pad ,please give some guidelines

    Quote Originally Posted by seseandy
    thanks!
    The Selection criteria is

    1) Speed (frequncy of operation, single ended or differntial)

    2) Type of load.

    3) Power



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    seseandy
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    Re: How to select I/O pad ,please give some guidelines

    Anyone can give some documents about I/O pad selection?

    thanks!!!!!!



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    How to select I/O pad ,please give some guidelines

    slow rate , driver strength, current, speed requirement. etc.



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    Re: How to select I/O pad ,please give some guidelines

    Hi seseandy,

    IMO, selecting an I/O pad is very subjective, it basically depends:

    1. Max speed of the pad
    2. input/ output / bi-directional
    3. with or without open drain output
    4. driving strength/ current/power/ wire load of the pad (this usually rely on how much current to drive the circuit).
    5. pull-up, pull-down or none
    6. with or without schmitt trigger
    7. with or without ESD protection
    8. Size (it might be critical in some design).


    regards,
    always smart



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    Re: How to select I/O pad ,please give some guidelines

    hi Always_Smart,

    Can you elaborate further on purpose of the Open-Drain output and Schmitt Trigger features..?

    Thanks



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    Re: How to select I/O pad ,please give some guidelines

    Quote Originally Posted by giggs11
    hi Always_Smart,

    Can you elaborate further on purpose of the Open-Drain output and Schmitt Trigger features..?

    Thanks
    ---------------------------------------------------------------------------------
    Hi giggs11,

    YOu need a pull-up resistor for the Open-drain output, in I2C standard this kind of output is particularly needed.

    For the schmitt trigger, it usually use in the clock input to prevent "spike" in the input signal.

    regads,
    always@smart



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