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LSF0102: LSF0102 (Vref_B= 3.3V and Vref_A= Hi-Z)

user5163805
Prodigy 20 points
Part Number: LSF0102
Other Parts Discussed in Thread: TCA9800, TCA9406, TXS0102, TCA9416

The following is described in FAQ 5.6 of the application note (Voltage-Level Translation With the LSF Family (Rev. B)) of the level shifter LSF0102YZTR.

Question
When VrefB= 3.3V and VrefA= Hi-Z, does the voltage of VrefBpropagate to VrefA(the voltage of VrefArises)? How much would the voltage rise if it propagated?
Also, is there a possibility that the voltage of VrefBwill sneak around the A1 and A2 terminals?

  • 0
    TI__Mastermind 38075 points

    Hi,

    By Hi-Z i believe you are trying to refer to Single Supply Translation similar to the referenced training video; helping to clarify your concerns, thanks.

    Best Regards,

    Michael.

  • +1 in reply to Michael Ikwuyum
    Prodigy 20 points

    We thank you for your answer.
    We would like to give a supplementary explanation of the circuit around our LSF0102.
    Vref_B applies a fixed voltage of 3.3V, and switches between 1.2V and 1.8V depending on the system.
    Therefore, it is not possible to configure the circuit around the LSF0102 using a single Vref_B power supply, such as VIDEO (Single Supply Translation with the LSF Family).

  • +1 in reply to user5163805
    Guru 297310 points

    Hi-Z is not the same as grounded.

    During normal operation, a current flows into Vref_B and out of Vref_A. So if the A-side power supply is Hi-Z, that current might power it up partially.

    To disable the LSF, you must pull EN low. Alternatively, use a level translator with a different architecture, e.g., TCA9416, TXS0102, TCA9406, or TCA9800.