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TXS0108E: Level Translator recommendation for Wiegand Interface

SRC
Intellectual 260 points
Part Number: TXS0108E
Other Parts Discussed in Thread: SN74LVC8T245

Hi,

We are working on custom design using MSP430. The system should accept Wiegand Input Data and also need to generate Wiegand data output. The IO levels of MSP430 is in 3.3V domain and the wiegand Output Port should be in 5V domain. We are using TXS0108 for level shifting from 3.3V to 5V. 

With TXS0108, the data transmission is successful upto 20cm. When we increase the length beyond 20cm, we are getting oscillations. If we add 1K Pull-Up at 5V side, oscillations are reduced and the range has increased upto 40cm. But beyond 40cm, its not reliable.

As TXS0108 has low drive strength and also as per the following e2e thread, TXS0108 should not be used for longer distance.

We need to support 5V Wiegand output upto atleast 50meter cable length. Can anyone suggest any efficient solution for the same?

  • 0
    TI__Guru 61590 points
    Hi Sankara,

    The auto bidirectional devices like the TXB or the TXS are not suitable for driving long traces with cap loading beyond 70pF.

    I would suggest using the DIR controlled device like the SN74LVC8T245 for 3.3 to 5V translation which can drive up to 32mA per channel to overcome cap and resistive loading. It can support up to 300Mbps for up/down translation.
    Let me know