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TXB0304: about TXB0304 application

Vera Mao
Expert 5065 points
Part Number: TXB0304

hi dear supporting team,

customer is using TXB0304 in below way, they are using it for isolate the connection with FPGA with enable function, to avoid when FPGA is not powering up, FPGA pull the SPI bus. both side are 1.8V level, according to our d/s,

1. output could not be pulled up, so they only use pull up at input,  R1 want to be higher than 20k, others using 4.7K

2. When open oneshot, the MOS internal resistance is almost 0, they add serial resister at TX side.

could you help check whether it is ok or not for the design? tks a lot!

  • 0
    TI__Mastermind 30545 points

    Hello Vera,

    Having pull-up resistors on the inputs should be fine, but there should not be any strong pull-ups ( < 20k ) on the outputs. Since the pull-up on the MISO line is 20k it should be fine.

    I am not sure what they are trying to do with the serial resistors. It sounds like they are trying to increase the output resistance during the one-shot operation? It should not cause any issues but I do not understand the reasoning.