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    Question about electronic terms (SMII/SS-SMII, TX, RX)

    Hi
    Following sentences are some parts of a datasheet, please take a look at them and tell the difference between the marked terms.

    • In SMII/SS-SMII, TXD1 is not used and should be tied either high or low.
    • In SMII/SS-SMII, RXD1is not used and they are driven low.
    • RMII mode;no switch controller is connected; and TX_EN[7:0] is pulled down.
    • 'Pd' stand for internal pull down (75K ohm)


    Thanks in advance.

    •   Alt1st January 2017, 05:50

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  2. #2
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    Re: Question about electronic terms (SMII/SS-SMII, TX, RX)

    Quote Originally Posted by HOSSEINGHODS View Post
    Hi
    Following sentences are some parts of a datasheet, please take a look at them and tell the difference between the marked terms.

    • In SMII/SS-SMII, TXD1 is not used and should be tied either high or low.
    • In SMII/SS-SMII, RXD1is not used and they are driven low.
    • RMII mode;no switch controller is connected; and TX_EN[7:0] is pulled down.
    • 'Pd' stand for internal pull down (75K ohm)


    Thanks in advance.
    Tied high means connected to Vcc using some current limiting resistor.

    Tied low/driven low/pulled down/internal pull down means connected to gnd again using current limiting resistor.



    •   Alt1st January 2017, 14:57

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  3. #3
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    Re: Question about electronic terms (SMII/SS-SMII, TX, RX)

    Thanks, some other questions;
    1. consider a pin which is internally pulled up (with an internal 75 K ohm resistor), is it necessary to pull this pin up externally? I have seen people doing this!
    2. what does keep logic low level mean?



    •   Alt2nd January 2017, 07:15

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  4. #4
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    Re: Question about electronic terms (SMII/SS-SMII, TX, RX)

    1. I think adding an external pull up resistor will leads to a strong pull up for that particular pin.

    2. "keep logic low" --> connecting the specific pin to logic '0' voltage or pulled down.


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