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About CAN Transceiver EN state on the sleep mode

GARAM AN
Intellectual 1990 points

Hi all,

I could find this picture on the CAN Transceiver datasheet, and I wonder the state of EN pin on the sleep mode.

I knew that the only state on EN is High or Low, I could know that EN of the CAN Transceiver is LOW at first and it changes to HIGH when the mode is changed to the Normal.

I could see the state of EN is x, I do not understand the x meaning.

It's written that "the enable pin can be in a logical high or low state on the sleep mode" I also do not understand what this meaning.

Could you please explain me detail for this?

  • 0
    TI__Guru 62920 points

    Garam,

    "X" simply means that the state of the pin is not relevant.  It could be either high or low without any difference in effect in this mode.

    Regards,
    Max

  • 0 in reply to Miguel Robertson
    TI__Intellectual 1990 points

    Thank you Max,

    I could see the "CAN:weak ground" on the Standby mode, go to sleep mode, and sleep mode, could you please explain what the weak ground means?

    I could find the INH:floating on the sleep mode on the picture.

    I know that the INH has two state (high, high Impedance), when it is high, output is Vsup-Vfet_diode, when it is high impedance, output is floating.

    Can I think high impedance is INH Low?

    What is the meaning of floating when INH is high impedance?

    Thank you

    INH floating

  • 0 in reply to GARAM AN
    TI__Guru 62920 points

    Hello,

    "Weak ground" means that CANH and CANL are biased to ground via the input resistances of the receiver; you can reference Figure 20 in the datasheet for an equivalent schematic and some more information.

    "High impedance" on INH means that it acts as an open circuit - i.e., it sources/sinks minimal current.  If you wanted to ensure that this "floating" output results in a low state, you could use a pull-down resistor to connect INH to ground.  A value like 100 kOhm is common and would allow the voltage to be near 0 V when INH is high impedance without sinking much current when INH is pulled up to VSUP.

    Regards,
    Max