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TXS0102-Q1: TXS0102DCUR VS TXS0102QDCURQ1 one-shot issue

arrow.yang
Prodigy 30 points
Part Number: TXS0102-Q1
Other Parts Discussed in Thread: LSF0102, LSF0002, TXS0102,

Dear,

         We are using TXS0102DCUR (main source) and TXS0102QDCURQ1 (second source) at our mass production project.  Now we meet an unexpected issue：

Issue phenomenon:

         We capture some fail waveforms at the same board, using TXS0102DCUR VS TXS0102QDCURQ1. From the failed waveform, we suppose it triggers one-shot feature.

It confuses us: there is only one pulse when using TXS0102DCUR, but there are 3 pulses when using TXS0102QDCURQ1? We want to know which parameter of TXS0102DCUR or TXS0102QDCURQ1 causes the difference: one pulse or three pulses.

Q1：

About the one-shot feature, what are the main differences between TXS0102DCUR and TXS0102QDCURQ1? What are the Vt (trigger one-shot threshold voltage) of TXS0102DCUR VS TXS0102QDCURQ1.

which will trigger one-shot more easily? 

Q2：

How wide are the pulse durations of TXS0102DCUR and TXS0102QDCURQ1, when trigger one-shot feature?

Q3：

Why are the number of pulse waveforms different at the same board?  One pulse when using TXS0102DCUR, while three pulse when using TXS0102QDCURQ1。

Q4：

The operation temperature of TXS0102DCUR is -40°C~85°C, it is Industrial grade? The datasheet didn't say it is Industrial grade. Our customer wants to know whether TXS0102DCUR is industrial grade or not.

TXS0102QDCURQ1 meet three abnormal pulses:

TXS0102DCUR meet an abnormal pulse:

waveform test point：

  • 0
    Guru 272490 points

    To insert an image, use "Insert" / "Image" below the text box.

  • 0 in reply to Clemens Ladisch
    Prodigy 30 points

    upload image.

    waveform test point:

    circuit

    XS0102DCUR meet an abnormal pulse:

    TXS0102DCUR unexpected 1 pulse

    TXS0102QDCURQ1 meet three abnormal pulses:

    TXS0102QDCURQ1 unexpected 3 pulses

  • 0 in reply to arrow.yang
    Guru 272490 points

    The one-shot triggers when a rising edge at a pin reaches about 30 % of that VCC (the exact threshold is not specified).

    In all the waveforms shown above, the voltage indeed rises before the one-shot. I see nothing abnormal in the behaviour of the TXS. Why do you say that these pulse are unexpected?

    If you do not want to get a complete pulse from a 30 % voltage, use a level shifter without edge acccelerators, e.g., LSF0002 or LSF0102.

  • 0 in reply to Clemens Ladisch
    Prodigy 30 points

    Thanks for your reply! we need your help to answer the below question.

    1、Why are the number of pulses are different at the same board?  One pulse when using TXS0102DCUR, while three pulse when using TXS0102QDCURQ1.

    Is that any difference between TXS0102DCUR and TXS0102QDCURQ1? 

    2、Do you mean:  when rising edge reach 1.8V * 30% = 0.54V , then trigger one-shot?

    as the below picture, the pulse overshoot is bigger than 0.6V, why not trigger one-shot?


  • 0 in reply to Clemens Ladisch
    Prodigy 30 points

    we check the datasheet of: LSF0002 or LSF0102, they are not PIN to PIN compatible with TXS0102DCUR. This design is MP and we don't have chance to update design at this schedule.

  • 0 in reply to arrow.yang
    Guru 272490 points

    1. There are three pulses because the voltage on the clock lines rises three times. This is not caused by the TXS; whatever I²C device is driving the bus is not pulling the bus low at that time. It looks as if that other device wants the line to go high.

    2. The threshold is not very exact. (And there is an additional requirement of a certain minimum slew rate, which is not documented.)

  • 0 in reply to Clemens Ladisch
    TI__Mastermind 23651 points

    Hey Arrow,

    Q1：About the one-shot feature, what are the main differences between TXS0102DCUR and TXS0102QDCURQ1? What are the Vt (trigger one-shot threshold voltage) of TXS0102DCUR VS TXS0102QDCURQ1.

    The two ratings of the TXS0102 have similar one-shot threshold (not quantified, but likely to be 30~40% VCC).

    Q2：How wide are the pulse durations of TXS0102DCUR and TXS0102QDCURQ1, when trigger one-shot feature?

    The O.S circuits are designed to stay on for approximately 30ns as stated in section 8.3.3 of datasheet. 

    Q3：Why are the number of pulse waveforms different at the same board?  One pulse when using TXS0102DCUR, while three pulse when using TXS0102QDCURQ1。

    The two devices are receiving different inputs, similar to Clemens' response above. 

    Q4：The operation temperature of TXS0102DCUR is -40°C~85°C, it is Industrial grade? The datasheet didn't say it is Industrial grade. Our customer wants to know whether TXS0102DCUR is industrial grade or not.

    Yes, commercial grade is equivalent to industrial grade. These terms can be used interchangeably. 

    Regards,

    Jack 

  • 0 in reply to Clemens Ladisch
    Prodigy 30 points

    Hi  Clemens,

           You are right. The low level from host is about 600mv and the first rising stage (as you circled above) is rising back to the low-level stage (about 600mV) but it triggers one shot. We want to know why TXS0102DCUR only trigger one pulse while TXS0102QDCURQ1 can trigger three pulses at the same board. what can make the difference?

  • 0 in reply to Jack Guan
    Prodigy 30 points

    Hi Jack,

        Thaks for you detail reply!

    we want to know more detailed.

    Q1：About the one-shot feature, what are the main differences between TXS0102DCUR and TXS0102QDCURQ1? What are the Vt (trigger one-shot threshold voltage) of TXS0102DCUR VS TXS0102QDCURQ1.

    The two ratings of the TXS0102 have similar one-shot threshold (not quantified, but likely to be 30~40% VCC).

    Arrow: Do you mean TXS0102DCUR and TXS0102QDCURQ1 have the same similar one-shot threshold but not quantified, but likely to be 30~40% VCC?

    Q2：How wide are the pulse durations of TXS0102DCUR and TXS0102QDCURQ1, when trigger one-shot feature?

    The O.S circuits are designed to stay on for approximately 30ns as stated in section 8.3.3 of datasheet. 

    Arrow: yes, we can find the 30ns sate at TXS0102DCUR spec. But we can't find the duration state at TXS0102QDCURQ1 spec.

    Q3：Why are the number of pulse waveforms different at the same board?  One pulse when using TXS0102DCUR, while three pulse when using TXS0102QDCURQ1。

    The two devices are receiving different inputs, similar to Clemens' response above. 

    Arrow: right. but We want to know why TXS0102DCUR only trigger one pulse while TXS0102QDCURQ1 can trigger three pulses at the same board. what can make the difference?

    Q4：The operation temperature of TXS0102DCUR is -40°C~85°C, it is Industrial grade? The datasheet didn't say it is Industrial grade. Our customer wants to know whether TXS0102DCUR is industrial grade or not.

    Yes, commercial grade is equivalent to industrial grade. These terms can be used interchangeably. 

    Arrow: understand, Thanks!

  • 0 in reply to arrow.yang
    Guru 272490 points

    The rising edges that I've marked with the circles do not come from the TXS, but from some other I²C device. Using the -Q1 device or not should not make any difference. It's probably chance, or some other difference. Did you try to solder the (non)-Q1 TXS to the other board?

  • 0 in reply to Clemens Ladisch
    Prodigy 30 points

    Hi  Clemens

       Yes, I agree with the rising edges do not come from the TXS. I want to know why there are three pulses using -Q1, but only one pulse when using TXS0102DCUR. Can we say that the Vt (voltage threshold) of TXS0102QDCURQ1 is more sensitive than TXS0102DCUR? or -Q1 is easier to trigger one shot?

  • 0 in reply to arrow.yang
    Guru 272490 points

    There are three pulses because there are three rising edges. Both the TXS0102 and the TXS0102-Q1 generate three pulses when they see three rising edges.

    I do not know why that other device generates three rising edges. You have to look at that other device.

  • 0 in reply to Clemens Ladisch
    TI__Mastermind 23651 points

    Hey Arrow,

    Arrow: Do you mean TXS0102DCUR and TXS0102QDCURQ1 have the same similar one-shot threshold but not quantified, but likely to be 30~40% VCC?

    Yes this is correct. 

    Arrow: yes, we can find the 30ns sate at TXS0102DCUR spec. But we can't find the duration state at TXS0102QDCURQ1 spec.

    The duration of the one shot should be similar for both the commercial (non-Q1) and automotive (Q1) grade device. 

    Regards,

    Jack 

  • 0 in reply to Jack Guan
    Prodigy 30 points

    Hey，Jack，

           With TXS0102DCUR waveform, there is also voltage rising (yellow arrow) following the pulse, and the rising is similar to the first rising (red  arrow). Why the second voltage rising (yellow) doesn't trigger one-shot?

  • 0 in reply to arrow.yang
    TI__Mastermind 23651 points

    Hey Arrow,

    Note the one shot threshold is a within a region and not exact value. You may also see section 3 of Do’s and Don’ts for TXB and TXS Voltage Level-Shifters with Edge Rate Accelerators for further clarification. 

    Regards,

    Jack