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TXB0304: Power supply recommendation (Datasheet modification from Rev.F to Rev.G)

Kawai
Guru 19775 points
Part Number: TXB0304
Other Parts Discussed in Thread: TXB0302

Hi Team,

We noticed that power down sequence had been added to the latest TXB0304 datasheet (SCES831G).

Please allow me to clarify following information to explain customers.

Q1). What could happen if the user did NOT power down both VCCA and VCCB together ?

Q2). What is the specific condition of power down "together" ?
   --> There could be cases when VCCA > VCCB, VCCA <  VCCB, or VCCA = VCCB. What is the criteria for the device to show unexpected operation ?

Q3). Is this power down requirement also applied to the TXB family devices, such like TXB0302 or TXB010x ? If they are, please update the datasheet the same way with PCN.

Best Regards,

Kawai

  • 0
    Guru 295240 points

    I'd guess that while one side is being powered down, but not yet at 0 V, the I/O voltage might appear to change, and trigger the edge accelerators at the other side.

    Furthermore, when the power on one side is at 0 V, the other side gets disabled, which means that the I/Os are now floating.

  • 0
    TI__Guru 59460 points

    Kawai,

    The power sequencing was modified as we had observed higher supply currents (on few devices) when one of the supply was turned off and the other was left turned on. Hence, recommend that either both supplies are ramped down together or within few seconds of each other. Once turned off, either one of the supply can be turned on without observing high supply current.

    This is not applicable for the TXB010x family but observed on the TXB0304 device only. I haven't tested the TXB0302 specifically. Will let modify the datasheet if we find anything similar.

  • 0 in reply to ShreyasRao
    Guru 19775 points

    Hi Clemens-san,

    Thanks for your comment.

    Hi Shreyas-san,

    Thank you for the information. This helps us very much to understand the background.
    Please allow me to clarify two things.


    Q4). If the device was not powered down together on A and B side, how much was the increased supply current ?

    Q5). During the high supply current flowing, could there be a possibility for the device to get damaged ?

    Best Regards,

    Kawai

  • 0 in reply to Kawai
    TI__Guru 59460 points

    Hi Kawai,

    There is no damage to the device when the power supply recommendations are not followed. I had observed about additional 50uA of current on the powered up supply side; which will affect the overall system power consumption. Once the device is reset, the current is in 100s of nA.

  • 0 in reply to ShreyasRao
    Guru 19775 points

    Hi Shreyas-san,

    Thanks for the support !!

    Best Regards,

    Kawai