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TXS0108e--Problem with the faliing edge of the signal

Aayush Gupta
Prodigy 30 points
Other Parts Discussed in Thread: TXS0108E

Hi,

I am using the TXS0108e voltage translator to translate logic from 1.8V(from Xilinx FPGA) to 3.3V for a DAC peripheral using SPI interface. 

The clock signal after the voltage translator has a slow fall time of around 60ns for a clock of around 6Mhz. While falling the signal starts to rise for some time and then falls again.

What can I do to reduce this fall time?

  • 0
    TI__Mastermind 31185 points
    Hello Aayush,

    It looks like the One-Shot is expiring which is causing the signal to fall slowly. Can you provide a shot of the input signal and a schematic? This would help to debug your issue.
  • 0 in reply to aozer
    Prodigy 30 points

    Hello aozer,

    Thanks for replying. Here is shot of my input. Also, will increasing the frequency help the cause(that is my ultimate aim). This is presently a 6Mhz clock and I want to increase it to 24 Mhz.

    Also, find the snap of my circuit.

  • 0 in reply to Aayush Gupta
    TI__Mastermind 24036 points

    Hello Auyush,

    Can you show use your test setup and how you are measuring your waveforms.  You have a lot of ringing in there and I want to know how much of it is real. Pictures of the setup and how you are probing would be helpful in understanding what we are seeing.

    -Sincerely,

    Francis Houde

  • 0 in reply to fhoude
    Prodigy 30 points
    Hi Francis,

    I am probing at the outputs of the IC directly. The bandwidth of my oscilloscope is 100 Mhz. Does that sufficiently answer your question?

    Best,
    Aayush
  • 0 in reply to Aayush Gupta
    TI__Expert 6335 points
    Aayush,

    I have a request:

    1. Can you send us the actual schematic? You can e-mail to us if you are uncomfortable with posting it on a public forum.
    2. Can you provide an oscilloscope waveform capture of the input into the TXS0108E and the output of the TXS0108E (on the SAME screen).
    3. Please make sure you screen capture contains key settings such as horizontal/vertical timescale, trigger level, etc

    Best Regards,
    Nirav