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TXB0108: TI solution suggestion

Jimmy Lai
Expert 6845 points
Part Number: TXB0108
Other Parts Discussed in Thread: TXS0108E, LSF0108

Dear Team,

We are looking for a level shifter for the NAND flash interface. 

  1. CPU NAND IO is 1.8V and NAND flash is 3.3V.
  2. CPU NAND interface supports up to 35MHz.
  3. NAND IO data is 8bit.
  4. Bidirectional
  5. No need direction-control

 

Is TXB0108 ideal for the application, or is there any other ideal part?

Please kindly recommend.

Many Thanks,

Jimmy

  • 0
    Guru 317150 points

    The TXB works only with very low loads, i.e., short traces, and no pull-up/-down resistors. For 1.8 V/3.3 V conversion, it supports up to 60 Mbps = 30 MHz.

    The TXS0108E has pull-ups on all pins, and supports the same speed.

    The LSF0108 can support higher speeds, but only with very strong pull-up resistors, which require strong output drivers on all devices.

  • 0 in reply to Clemens Ladisch
    TI__Expert 6845 points

    Hi Clemens,

    We appreciated your great support!

    1. How do you convert Mbps to MHz? 60 Mbps= 30 MHz?

     

    1. About the strong pull-up resistor you mention in LSF0108, it should be the 200K for the enable signal, right?

     

                 If so, all we need is to make sure an open drain driver used at the enable pin as below?

               

    Many Thanks,

    Jimmy

  • 0 in reply to Jimmy Lai
    TI__Mastermind 45915 points

    Hey Jimmy,

    1. Yes that is correct, the rule of thumb is that Hz = 2 x bps

    2. The 200k biasing resistor isn't the pull-ups Clemens was referring to. He was referring to the pull-ups needed at the I/O(refer to video 6 in that same training series). If you plan on controlling the EN pin then yes you would need to do it with an open-drain driver.