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TXS0104E - Does it support the 'Vcc Isolation' feature?

Sadanori Kato
Guru 36540 points
Other Parts Discussed in Thread: TXB0102, TXS0102, TXS0104E, TXS0108E

Hi,

Are all outputs placed into the high impedance state if either VCCA or VCCB is at GND such as TXB0102 and TXS0102 ?
Could you please give us your advice since that information isn't mentioned in the TXS0104E data sheet ?

Best regards,
Kato

  • 0
    TI__Expert 6335 points

    Sadanori,

    TXS0104E does support VCC isolation. I will have to figure out why it is not mentioned in the 'Features' section of the datasheet.

    There is no specific datasheet parameter that covers VCC isolation. I went in the lab to verify.

    For level translators, VCC isolation is a feature that will disable the input, output, or combined input/output ports that are referenced to a powered-on supply rail when another supply rail is powered down. For the TXS0104E:

    1. If VCCB is powered down to 0V, then pins A1, A2, A3, and A4 are high impedance
    2. If VCCA is powered down to 0V, then pins B1, B2, B3, and B4 are high impedance.

    I verified in the lab using the procedure below:

    1. Set VCCA = 1.80V and VCCB = 3.30V and OE = 1.80V
    2. Force A1 pin to GND and B1 pin to 3.30V
    3. Measure current draw on B1 --> 55 mA [current flow from B1, through TXS0104E, to A1 and therefore down to GND]
    4. Force VCCA to 0V
    5. Re-measure current draw on B1 --> 0.0003 uA [VCCA isolation causes B1 to switch to High-Impedance]

    1. Set VCCA = 1.80V and VCCB = 3.30V and OE = 1.80V
    2. Force B1 pin to GND and A1 pin to 1.80V
    3. Measure current draw on A1 --> 58 mA [current flow from A1, through TXS0104E, to B1 and therefore down to GND]
    4. Force VCCB to 0V
    5. Re-measure current draw on A1 --> 0.0001 uA [VCCB isolation causes A1 to switch to High-Impedance]

    Best Regards,
    Nirav

  • 0 in reply to Nirav Patel
    Guru 36540 points

    Hi Nirav-san,

    Thank you for your verification.
    According to your verification, I was confused a little bit since it seems that TXS0108E supports not only the VCC isolation feature but also the Ioff feature although these aren't mentioned in the TXS0108E data sheet.
    How does TXS0104E work if verifying TXS0104E as well ?
    Could you please look into this and get back to me ?

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 36540 points

    Hi Nirav-san,

    Do you have any updates for my question ?

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 36540 points

    Hi Nirav-san,

    I know you are busy, however could you please let me know whether TXS0104E has the VCC isolation and Ioff features such as TXS0108E since we should inform our customer of it by tomorrow ?
    Your quick response would be greatly appreciated.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Expert 6335 points

    Kato-San,

    TXS0104E does support VCC isolation. I updated my previous post with data taken on the TXS0104E.

    TXS0104E does not support Partial Power Down Mode. I believe that I addressed this in this E2E post.

    Best Regards,
    Nirav

  • 0 in reply to Nirav Patel
    Guru 36540 points

    Hi Nirav-san,

    Thank you for your quick response.
    I understood and will inform our customer of these information.
    By the way, could you please tell me when those data sheets(TXS0104E and TXS0108E) are revised about the VCC isolation feature ?

    Best regards,
    Kato