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TLIN1021A-Q1: Pin FMA for Device Pins Short-Circuited to VSUP supply

kentarou.harada
Prodigy 20 points
Part Number: TLIN1021A-Q1

Hi TI Expert,

I have a question about chapter 4 of the Application Report "TLIN1021A-Q1 Functional Safety FIT Rate, FMD and Pin FMA (Ver: SLLA540 - DECEMBER 2020)" of the product model number "TLIN1021ADRB-Q1".

URL：TLIN1021A-Q1 Functional Safety, FIT Rate, Failure Mode Distribution and Pin FMA

In Table 4-5, "Pin FMA for Device Pins Short-Circuited to VSUP supply",

Are these short-circuit events intended for shorts that can occur inside the IC?

In particular, I would like to know if RXD, EN, and TXD can be short-circuited to VSUP in the internal circuit of the IC.

Thank you.

  • +1
    TI__Mastermind 26806 points

    Harada-san,

    Thank you for posting! I am happy to help clarify.

    Table 4-5 in that document helps to clarify what the effects of accidentally connecting to VSUP externally. This does not reflect any risk of the pins becoming spontaneously connected to VSUP internally.

    For your system, this helps you analyze the possible impacts of issues that come up during soldering, assembly, or manufacturing of your final project. For example, your company might determine some percent risk of possibility that a particular signal or rail could accidentally be connected to VSUP on your PCB or externally. This Pin FMA shows what the impact to the TLIN1021A-Q1 would be.

    If VSUP is greater than the absolute maximum rating of a particular pin, then it risks damaging the TLIN1021A-Q1 due to overvoltage. However, this is not showing a risk of pins like RXD, EN, TXD, or others of spontaneously internally becoming connected to VSUP.

    Best,

    Danny

  • 0 in reply to Danny Bacic
    Prodigy 20 points

    Dear Danny,

    Thank you very much for your answer.
    I now have a better understanding of Table 4-5.
    I would like to continue with an additional question.

    ・Apart from pin FMA, is there any possibility that RXD, EN, and TXD can be internally shorted to Vsup?
    　（For example, in my opinion, there is no possibility of RXD having an internal short to Vsup. Is this idea correct?）

    ・Could you tell me the possible voltage values of the RXD, EN, and TXD pins in the event of an internal failure of the IC?
    　(For example, TXD will not be at Vsup level, but it can be at 5V level which is produced inside the IC, etc.)

    Thank you for your responses to the above two points.

  • 0 in reply to kentarou.harada
    TI__Mastermind 26806 points

    Harada-san,

    When there is a single-point random failure within the device, these usually present as a functional failure that shorts the pin to GND. However, catastrophic failures of the device (as in from an overvoltage or overtemperature condition) can cause unpredictable results, so I wouldn't be able to guarantee how exactly the device might fail.

    Rails such as RXD, EN, and TXD are intended to be connected to MCUs that communicate using lower-voltage rails, so they are referenced based upon an internal step-down within the device to logic level voltage.

    In short, it sounds like your understanding in the parentheses above is correct.

    Best,

    Danny

  • 0
    Prodigy 20 points

    Part Number: TLIN1021A-Q1

    Dear TI Expert,

    ・Is there any possibility that RXD, EN, and TXD can be internally shorted to Vsup?
    　（For example, in my opinion, there is no possibility of RXD having an internal short to Vsup. Is this idea correct?）

    ・Could you tell me the possible voltage values of the RXD, EN, and TXD pins in the event of an internal failure of the IC?
    　(For example, TXD will not be at Vsup level, but it can be at 5V level which is produced inside the IC, etc.)

    Best regards,

    Kentaro Harada

  • 0 in reply to kentarou.harada
    TI__Mastermind 26806 points

    Harada-san,

    It looks like this was double posted. Please see above.

    Best,

    Danny