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TCA39306: Need help in using TCA39306DDFR with I3C and legacy I2C devices

Krunal Zala
Prodigy 120 points

Part Number: TCA39306

Hello,

I am considering TCA39306DDFR  for my new development work.

Below is the block diagram of my intended circuit.

   

I have following queries pertaining to above proposed block diagram using TCA39306DDFR  

  1. Do I need to use pull up resistors on I3C bus considering the fact I have two legacy I2C devices?
  2. If I have to use pull up ressitors on I3C bus, shall I use those pull resistors at 1.8V side or 3.3V side?

Alternatively, you can redirect me to suitable material from where I may get clarification to above technical queries.

Regards,

  • 0
    TI__Guru 65498 points

    Hi Krunal,

    Krunal Zala said:
    Do I need to use pull up resistors on I3C bus considering the fact I have two legacy I2C devices?

    The TCA39306 does not have integrated pull-up resistors. Since the I3C primary controller most likely integrates the pull-up resistor for I2C mode, you will need a pull-up resistor on the 3.3 V side of the translator, even during push-pull I3C mode. 

    Krunal Zala said:
    If I have to use pull up ressitors on I3C bus, shall I use those pull resistors at 1.8V side or 3.3V side?

    Only the 3.3V side is required if the primary controller integrates the pull-up resistor. 

    To be safe, you can add a pull-up resistor to the 1.8V side and de-populated the part for future use. 

    Regards,

    Tyler