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TXB0108: Compatibility Question with Memory Intereface

Chris Lee
Prodigy 20 points

Part Number: TXB0108

Hi, 

Initially, I evaluated the level shifter’s compatibility with the memory interface based on voltage levels and data rate. Are there other electrical characteristics I should consider that could impact compatibility between the memory interface and the level shifter?

For example, should DC electrical characteristics be evaluated as well? Memory DC electrical characteristics attached below..

Memory DC electrical characteristics: memory_spec.jpg

Thanks,

  • 0
    TI__Guru 61061 points

    Hi Chris,

    To ensure compatibility, the logic thresholds should be within each other. For example if the configuration is controller -> TXB0108 -> Memory, please ensure that the min. VOH of the TXB0108 is above the min. VIH of your memory device, and that the max VOL of the TXB0108 is below the max VIL of the memory device. 

    The opposite also must hold true if Memory will be communicating back into the TXB0108 -> Controller:

    Regards,

    Jack

  • 0 in reply to Jack Guan
    Prodigy 20 points

    Hi Jack,

    Thanks for replying. So, it seems that as long as the voltage level is within the range, there would be no other items we need to evaluate, right? I was wondering about two things:

    1. The TXB0108 works with 20 µA per test condition. Would that be sufficient for a memory bus?
    2. Also, according to the memory spec I attached, it can generate up to 140 mA for read/write operations, while the TXB0108 has the maximum ratings shown below. Would it be okay to utilize it with a memory bus?
      1. Input clamp current up to -50mA
      2. Output clamp current up to -50mA
      3. Continuous output current up to +/-50mA

    Thanks,

  • 0 in reply to Chris Lee
    TI__Guru 61061 points

    Hi Chris,

    I am still looking into this and will provide a response shortly.

    Regards,

    Jack

  • 0 in reply to Jack Guan
    TI__Guru 61061 points

    Hi Chris,

    1. It would be best to consult with the vendor for this question. The IOH/IOL limitation is due to the 4k series resistors at the output of this device, and enables the auto-bidirectional capability. 

    2. Similar to #1- it would be helpful to confirm with memory vendor if this is operating current during R/W states, though note that it is suggested to operate within the recommended operating conditions and not abs. max. 

    Regards,

    Jack