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TIDA-050026-23881: TCA9517A usage

Ann_Lien
Genius 9290 points
Part Number: TIDA-050026-23881
Other Parts Discussed in Thread: TCA9517A, TPS23881

Hello expert,

We have one question on TIDA-050026-23881. there is reserved TCA9517ADGKR, it seems like it is used to connect board to board. May we know if we have tested board to board communication? And what is the use scenario for this I2C repeater? Thanks a lot! 

Best regards,

Ann Lien

  • 0
    TI__Genius 16980 points

    Hi Ann, 

    Let me check internally and get back to you tomorrow COB. 

    Thanks and Regards,

    Raymond Lin

  • 0
    TI__Genius 16980 points

    Hi Ann, 

    Board to board communication should work without TCA9517A, we have this part reserved in case I2C traces are too long and we start encountering issues. On the motherboard we included 0Ohm resistors to bypass the TCA3517A so you can still test board to board without the repeater. As long as all the PSE devices across both boards have different I2C slave addresses (A0 through A3 pins might need to be modified) there should be no issues. 

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    TI__Genius 9290 points

    Hello Raymond,

    May I know if we have test result on this I2C buffer? customer would like to know if we have use case sharing. Customer would like to use 12pcs TPS23881 in their application and they would like to know if you have suggestion on the 12pcs TPS23881 placement. Thanks a lot!

    Best regards,

    Ann Lien

  • 0 in reply to Ann_Lien
    TI__Genius 16980 points

    Hi Ann, 

    For test results, are you referring to regression/validation testing including TCA9517A? I'll need to check internally if we have done so but generally speaking it's not needed unless we see I2C issues. 

    Regarding placement, are there any board size constraints or concerns customer might have? Usually I would recommend to make sure for each PSE the fets are placed on the same layer and as close as possible to the PSE GATEn pins. Each PSE should be placed near their respective ports (I assume each TPS23881 will be configured for 4-pair ports across all 8-channels). 

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    TI__Genius 9290 points

    Hello Raymond,

    Yes, they would like to know if they need to put or not the TCA9517A for their 12pcs TPS23881 application. Thanks!

    Best regards,

    Ann Lien

  • +1 in reply to Ann_Lien
    TI__Genius 16980 points

    Hi Ann, 

    A repeater is needed based on the cumulative bus capacitance on the I2C lines,

    More details can be found on this apps note: https://www.ti.com/lit/an/scpa054/scpa054.pdf?ts=1686320268756&ref_url=https%253A%252F%252Fwww.google.com%252F#:~:text=If%20the%20system%20requires%20having,I2C%20standard%2C%20see%20Figure%209. 

    If you have information regarding their board requirements (size, # of layers, etc.) we might be able to make a better recommendation on if they need to use it or not. On our FIRMPSE EVM, it's not used as we have not seen much I2C issues without it but different board designs can produce different results. 

    Thanks and Regards,

    Raymond Lin