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SN65HVDA100-Q1 design recommended

Eric Lo63813
Intellectual 450 points
Other Parts Discussed in Thread: SN65HVDA100-Q1, SN65HVDA100

Can you help us provide SN65HVDA100-Q1 design recommend.

Q1. If the wake-up function is not used, NWake should be connected to ground ? (Like freescale MC33662)

Q2. SN65HVDA100 Pin7 (NWake) recommended resistor value ?

Q3. Vbat to Vsup diode recommand?

Thank you~

 

 

  • 0
    TI__Mastermind 21831 points

    Eric,

    Sorry for the delay in getting back to you, I was out of the office last week.

    Q1. If the wake-up function is not used, NWake should be connected to ground ? (Like freescale MC33662)

    For the SN65HVDA100, the only time the NWAKE pin affects the mode is when the device is in sleep mode. If NWAKE is held low the device will go into sleep mode then immediately transfer into Standby Mode after tNWAKE. If the pin is held high (~VBatt) the device will have no local wake-up. It will remain in Sleep Mode until the EN pin is toggles high or a LIN bus Wake-Up request occurs. Therefore it depends how you want to use the device. This differs slightly from the Freescale device since when their device enters Sleep Mode it will save the current state of the WAKE pin and will leave Sleep mode whenever that pin is toggled. Therefore it could be either a low to high transition or a high to low transition that wakes the Freescale Part up from Sleep Mode. 

    Q2. SN65HVDA100 Pin7 (NWake) recommended resistor value ?

    The devices pin can be tied directly to ground (0Ω or 1Ω). If a resistor is used it needs to be small enough that the pull-up current does not cause a voltage across the external resistor large enough to not be seen as a logic low (voltage needs to be < Vsup - 3.3 volts).

    Q3. Vbat to Vsup diode recommend?

    I have seen both the 1N5711W and the BA260 diode used. 

    Please let me know if you need anything else, again sorry for the delay.

    John G

  • 0 in reply to John Griffith
    TI__Mastermind 21831 points

    Eric,

    Typo:

    I meant to say B260 diode, NOT BA260.

    John

  • 0 in reply to John Griffith
    Intellectual 450 points

    Dear John,

    Got it and thanks.

     

    Best regards,

    Eric Lo

  • 0 in reply to John Griffith
    Intellectual 450 points

    Dear John,

    Sorry, another question.

    Do you have MC33390EF (J1850) replace suggestion?

     

    Thanks for your support.

    Best regards,

    Eric Lo

     

  • 0 in reply to Eric Lo63813
    TI__Mastermind 21831 points

    Eric,

    The J-1850 Class B device you mentioned is a variable pulse width modulation single wire interface that TI does not offer any devices in. Unfortunately I can not help you with this. 

    John

  • 0 in reply to John Griffith
    Intellectual 450 points

    Dear John,

    The IN517W IFM : 15mA and B260 IFM: 2A. Which one for Vsup and Master Node ?

    Thank you~

  • 0 in reply to Eric Lo63813
    TI__Mastermind 21831 points

    Eric,

    Whatever you have on your purchasing list that meets the LIN standard for the diode drop, and the max current spec of the device. You can use everything from power diodes to signal diodes without any issues.

    • Parameter 21 of the LIN2.1 spec stats that the forward voltage drop of any serial diode cannot be greater than 1.0 volts (typical 0.7 volts)
    • The SN65HVDA100-Q1 maximum supply current (domimant state) is 7.5 mA (Parameter 4.5 of the datasheet)
    But, this current spec for our datasheet (7.5 mA) DOES NOT include fault conditions. For example the fault condition where the LIN bus gets shorted to ground. Therefore to err on the side of safety for any fault condition the maximum current would be parameter 7.3 in the datasheet (200mA) for a short to ground fault. 
    For this reason any diode that has a forward voltage drop of less than 1.0 volts and can handle a peak current of 200mA should would be the best bet. The B260 diode is the safer choice for withstanding fault conditions. Here is the B260 datasheet.
    Thanks,
    John