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SN65HVD77: Automotive alternative?

Michael
Intellectual 255 points
Part Number: SN65HVD77
Other Parts Discussed in Thread: SN65LBC179,

Tool/software:

Is there an automotive alternative for the part, SN65HVD77DGKR?

The closest one I found was SN65LBC179QDR, but it has the following differences:

  • Vcc = 5V (instead of 3.3V)
  • Max signaling rate = 10 Mbps (instead of 50 Mbps)
  • Larger footprint 8-SOIC  (instead of 8-MSOP)

Is there anything closer?

Thank you.

  • 0
    TI__Guru 72381 points

    Hi Michael,

    Unfortunately not, SN65HVD179Q (which you already found) is our only other full duplex device that includes the 'Q' (automotive range).

    Are you able to provide me with what kind of application you need this for? 

    If possible, can you also provide the number of units you would need for your application? 

    I can try to feed that information to our team to see if they want to consider automotive qualifying a commercial device. 

    -Bobby

  • 0 in reply to BOBBY
    Intellectual 255 points

    Hi Bobby, 

    This would be for a safety application. We would be most likely looking to purchase these in lots of 1000.

    Thank you,

    Michael

  • 0 in reply to Michael
    TI__Guru 72381 points

    Thanks Michael,

    I've sent this to our new product development team as something they can look into at a future date. 

    -Bobby

  • 0 in reply to BOBBY
    Intellectual 255 points

    Hi Bobby, 

    Thank you for the update.

    Just to confirm, is SN65HVD179Q indeed AEC-Q100 qualified? I see the temp range and the 'Q' in the P/N, but I noticed that the datasheet doesn't explicitly call out AEC-Q100 like some other TI components.

    Thanks,

    Michael

  • 0 in reply to Michael
    TI__Guru 72381 points

    Hi Michael,

    Michael said:
    Just to confirm, is SN65HVD179Q indeed AEC-Q100 qualified?

    Unfortunately not.

    As you noticed, the Q version only meets the extended temperature range that most automotive devices use. TI uses a suffix -Q1 when it has actually gone through the automotive qualifications. The SN65LBC179QDR (I referenced the wrong device in my earlier post of HVD179Q) has only been characterized for it's electrical parameters up to 125C ambient. It hasn't gone through the AEC-Q100 qualification process.

    -Bobby

  • 0 in reply to BOBBY
    Intellectual 255 points

    Hi Bobby, 

    Thank you for the clarification.

    I think there may be an error with TI's product filter for RS-485 & RS-422, as it lists SN65LBC179 as having an automotive rating:

    However, the SN65HVD77 is not, despite also having been characterized to 125C.

       

    In any case, since neither of these are AEC-Q100 qualified, what would be some reasons to use one over the other?

    Thank you,

    Michael

  • 0 in reply to Michael
    TI__Guru 72381 points
    Parameter SN65HVD77 SN65LBC179
    Vcc  3.3V 5V
    Full duplex or Half duplex Full duplex Full duplex
    Max Data rate 50Mbps 16Mbps (calculation = 1/(max diff rise|fall time x3)
    Common mode (max A/B/Y/Z voltage device can withstand if shorted) -13V to 16.5V -10V to 15V
    VoD 60 ohm load 2V typical 2.2V typical
    VIT+ (internal fail safe if negative) -20mV max 200mV max
    ViD hysteresis 70mV 45mV

    These are the specs I compared (and what I think matter when looking at an RS422/485 transceiver). 

    The VIT+ parameter has pros and cons so I didn't mark either one as better or worse. Negative means it has added protection when the device sees a short, open or idle which most customers prefer. But with how fast the data rate is, this can cause the bit distortion to lean towards logic '1's to be longer and logic '0's to be shorter than intended. And on the opposite end, having a 200mV VIT+ can helps with receiving at longer distances because there is less bit distortion but you lose the internal fail safe protection that having a negative VIT+ provides. At higher data rates, I would probably prefer the 200mV without internal fail safe but it depends on the system. 

    Note, faster data rate isn't always a good thing (which is why I didn't mark it as positive or negative). Generally you will have more reflections after the edge transition and if the bus is long or being used at a fast data rate you end up with reflections on the data stream. Also results in more EMI, so generally you pick the slower data rate if your system doesn't require a fast one. (Faster isn't better when required data rate is slow).

    -Bobby