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TXS0108E: Damage to the +3.3V System When Using TXS0108E

Conor
Guru 12450 points
Part Number: TXS0108E


Tool/software:

Hi,

We are currently experiencing an issue where the +3.3V system is being damaged in a circuit utilizing the TXS0108E.
We would like to understand the possible causes and countermeasures for this issue, and we would appreciate your guidance on the matter.

■ Circuit Configuration

In our design, we are using the TXS0108E with the following setup:

  • VCCA side (3.3V system): Push-pull I/O
  • VCCB side (5V system): Push-pull I/O
  • Bidirectional communication via TXS0108E

■ Issue Encountered

  • The +3.3V system is being damaged at an unknown timing, and this has occurred multiple times.
  • We would like to confirm with TI whether any of the following conditions could lead to such damage:
    1. If VCCA is powered, and a negative voltage (0V or below) is applied to the VCCB side, is there a possibility that current could pass through TXS0108E's internal resistors (R1/R2) and cause stress on the VCCA side?
    2. Under certain conditions, could a 5V signal from the VCCB side be directly transferred to the VCCA side, causing unexpected voltage levels?
    3. Are there any other precautions regarding the use of peripheral components that could lead to excessive load or damage to TXS0108E or the +3.3V system?

We have reviewed the datasheet specifications, but we would like to receive an official response from the manufacturer regarding these concerns.

Thanks,

Conor

  • 0
    TI__Mastermind 42781 points

    Hi Conor,

    1. Yes, it is likely for damage to occur to the device if there exists a voltage on VCCA higher then VCCB. This is due to an internal protection diode that becomes forward biased in the event that VCCA> VCCB, and is also the primary reason that the datasheet suggests operating in a VCCA<= VCCB manner to prevent this leakage current backflow between VCCA/ VCCB. This app note discusses these details further: https://www.ti.com/lit/an/scea060/scea060.pdf?ts=1740591106367

    2. No, 5V is within the recommended operating conditions of 1.65V~5.5V for VCCB. Please note that VCCA recommended operating conditions is 1.4V~3.6V.

    3. Section 5.1 Abs. Max Ratings details the limitations of the device that will cause certainly cause catastrophic damage to the device. 

    Regards,

    Jack