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TCA9800: use the TCA9800 as the I2C level shift,

Frank Xiao
Genius 12055 points
Part Number: TCA9800

Hi team,

My customer wants to use the TCA9800 as the I2C level shift, but the system is a little complex. They want to use the device at the red circuit as the picture below. Could you please help check the risks here? Thanks

  • 0
    TI__Guru 62920 points

    Hi Frank,

    Do you have any more information about the devices interfacing to one another, such as their supply voltages and IO characteristics (high and low input and output levels, input leakage current or resistance, etc.)? What specific concerns do you have regarding usage of TCA9800 in this application?

    Regards,

    Max

  • 0 in reply to Miguel Robertson
    TI__Genius 12055 points

    Hi Max, 

    The interface is I2C, the voltage is CPU and PEX8796 are 1.8V I/O, others are 3.3v. The risks here are they are not the same board. Do we have some experience about board connection. How to evaluate other risks? Thanks.

  • 0 in reply to Frank Xiao
    TI__Guru 72181 points

    Hey Frank,

    For the TCA980x, the B side cannot connect to any I2C switches/multiplexers/pass-FET level shifters/buffers with static voltage offsets or other TCA980x B sides.

    I would suggest that in your diagram you make the B side of TCA980x connect to the CPUs in the top half of your diagram. For the sections where it is connected to the PCA9545, I would suggest A side connect to the switch and B side connect to the CPU.

    Please ensure that the voltage rules for each TCA980x is being met.

    Let me know if you have further questions.

    -Bobby