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TCA9545A: VCC setting question

Andy_Lin
Intellectual 2590 points
Part Number: TCA9545A

Hi Team,

My customer is using TCA9545A as solution , their application will needed to use slave ch with 3.3V(SD/SC0) and 1.8V VCC(SD/SC1~3), they have below 2 questions to wanted to check,

1. Is this device support 1.8V and 3.3V for different pair output simultaneously?

I think this is yes, per our d/s , this device support level translation between 1.8-V, 2.5-V, 3.3-V, and 5-V buses.

2.In their using case as above figure shown, is VCC set as 3.3V OK or not?

per d/s , 6.5 Electrical Characteristics & 9.2.1 Design Requirements,

Vpass needed to be equal or lower than the lowest bus voltage(1.8V in your case), so setting VCC=3.3V might not be ok, I would recommend set VCC lower(2.5V or 1.8V) to be on the safe side.

please kindly help to check if my above suggestion are ok or not , let me know if I have misunderstand or missing points , thanks a lot!

  • 0
    TI__Guru 53535 points

    Hi Andy,

    Your understanding seems correct on this. Thanks for being thorough with your explanation. 

    1. Is this device support 1.8V and 3.3V for different pair output simultaneously?
    Yes, TCA9545A can translate between different downstream channel voltages as long as Vpass is set up correctly. 

    2.In their using case as above figure shown, is VCC set as 3.3V OK or not?
    The depicted configuration violates Vpass requirements. Vcc will have to be a lower value than the 3.3v in order to translate down to 1.8v. You may recommend using the 1.8v rail for TCA9545A's Vcc if it is readily available. 

    Regards,
    Eric