• State TI Thinks Resolved
  • Locked Locked
  • Replies 9 replies
  • Answers 1 answer
  • Subscribers 23 subscribers
  • Views 1527 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TXS0104E: One shot questions about TXS0104

Lacey Lin
Intellectual 2900 points
Part Number: TXS0104E


Hi team,

Please help to reply for the one shot related questions as below:

1. Because the TXS0104 can identify the data transmit direction, so for the one shot trigger level is the 1/2 Vin, so for below test signal:

The data direction is from A to B. Signal A is the 1.8V and signal B is 3.3V. So when the input voltage increase up to 500mV, the one shot is triggered. So the slew rate signal B increase. But at the same time, the slew rate of signal A also increase. Does the one shot also affect the input signal?

2.Is there any requirement for the slew rate of the input signal to trigger the one shot?

3.for the below input signal(A), is the one shoot triggered? Does the signal of the output make sense? it seems the output B cannot reach the 3.3V.

A input:1.8V, B output:3.3V

 

Lacey

Thanks a lot!

  • 0
    TI__Guru* 97066 points
    Hello Lacey,
    I have asked Shreyas to look at this for you - he should be back with you in the morning (Dallas time).
  • 0 in reply to Emrys Maier
    TI__Intellectual 2900 points
    Hi Emrys,
    Thanks for your help!
    Please help to check as soon as possible, customer are waiting for the answer to solve the problem!

    Lacey
    Thanks a lot!
  • 0
    TI__Guru 62600 points
    Hi Lacey,

    1) The oneshot is increasing the slew rate of the output signal even when the TXS internal FET is turned on. This momentarily increases the input signal before the FET is turned off.
    2) The transition rate specs in the ROC of the datasheet.
    3) The output final level will depend on the loading on the output, as well as the frequency of the signal.
    The greater the loading, the lower is the final output voltage level.
    the greater the frequency of the signal, the lower is the output voltage level( since the final level will have to be enabled using the internal pullup resistor and the cap loading (RC time constant) )
  • 0 in reply to ShreyasRao
    Prodigy 30 points

    1, my question is: is the normal waveform one-shot in the Lucy waveform? If so, why is there no voltage inflection point?

    2, as shown below, this is the normal one-shot waveform we understand, because there is an obvious voltage inflexion.

  • 0 in reply to ShreyasRao
    Prodigy 30 points

    1, my question is: is the normal waveform one-shot in the Lucy waveform? If so, why is there no voltage inflection point?

    2, as shown below, this is the normal one-shot waveform we understand, because there is an obvious voltage inflexion.

  • 0 in reply to ShreyasRao
    Prodigy 30 points
    The second waveforms emitted by Lacey have no voltage inflection point（such as the first waveform）. Do chips enter one-shot state?
  • 0 in reply to ShreyasRao
    TI__Intellectual 2900 points

    Hi ShreyasRao,

    Thanks for your reply!

    Another two questions:

    1.Can we identify the data direction by the signal wave? or just can by the delay?

    2. How can we identify if one shot function has been triggered? such as below picture, can we identify if the one shot function has been triggered in below picture?

    It seems the input voltage has been to Vcc/2, and the slew rate doesn't change.

    Lacey

    Thanks a lot

  • 0 in reply to Lacey Lin
    TI__Intellectual 2900 points

    Hi team,
    Please help to reply above questions, customer need a explanation to close this issue.

    Lacey
    Thanks a lot!

  • 0 in reply to Lacey Lin
    TI__Guru 62600 points
    Lacey,

    Direction identification on the scope can be done by the prop delay of the signal , however , since you set up the direction, it should be known while testing.
    one shot trigger can be identified by the fast rise time of the output signal around the Vcc/2 of the incoming signal.
    The rise time will be dependent on the loading on the output port, including the probe capacitance.
    With light or no loading, the slew rate will be fast.

    In order to test the oneshot function, have the input signal rise at very slow input slew rate, around Vcc/2, the one shot circuitry will trigger and will be on for about 15ns (at Vccx level) and once the one shot expires , the output will fall down before the 10k pullup will act and rises it up again to the Vccx level.