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Original question:

Is there a Level translator from 2.5V to 1.5V for I2C lines?

Selection of correct I2C Bus buffer IC for a backplane

doner_t
Intellectual 645 points
Other Parts Discussed in Thread: TCA9517, TCA4311A

Hello,

I have an I2C bus on a backplane. One master is driving the bus and the other slaves(3-5) listen to the bus. Backplane I2C bus total (PBC traces + connector + vias ..etc) capacitive loading budget  is near 175 pf. Only I2C bus PCB traces is near 75 pf.  Capacitive loading budget per each slave is near 22 pf. Max frequency is 400KHz. Please note that I will use this I2C buffer in Master and each slave boards. 

Thank you,

  • 0
    TI__Intellectual 2090 points

    Hello,

    What VCC range will you need for this I2C bus?  Also, will you need to be able to insert and remove boards from the system while the bus is active?  (Hot Swap, Hot Insertion, etc.)

    Best Regards,

    Max Megee

    Interface Transceiver Applications

  • 0 in reply to Max Megee
    Intellectual 645 points
    Hello,

    VDD is 3.3V. But 5V is more proper for this case? I2C bus length probably longer than 20cm on the Backplane. Slave number might be greater than 5. I dont prefer the Hot Insertion. But for protecting the bus, It could be used. a user who does not know can do insertion/extraction boards while bus is active. Hot swap/hot insertion will good for protecting bus.

    Best Regards,
  • 0 in reply to doner_t
    TI__Intellectual 2090 points
    You can take a look at the TCA9517. This part will operate with both 5V and 3V I2C buses. It has a low output capacitance on its pins, and it does not possess the Hot Swap feature.

    If you require the Hot Swap/Hot Insertion feature, you may look into the TCA4311A device. It also operates over 3V and 5V buses. However the TCA4311A does possess reduced performance over the TCA9517.


    Best Regards,
    Max