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TCA9509: solution checking

Hailiang Zhang
Genius 11340 points
Part Number: TCA9509
Other Parts Discussed in Thread: TCA9517, TCA9617B

Tool/software:

Hi Team,

If we are using TCA9509 or TCA9617, it is required to connect port A to port B when using multiple instances. But if we are using TCA9509 with TCA9617, and unfortunately we connect the same port, say TCA9509's port B to TCA9617's port B, will this cause any problems? Thank you.

Regards,
Hailiang

  • 0
    TI__Guru 50588 points

    Hi Hailiang,

    I would need to have a block diagram or schematic to give a more complete answer to your question. 

    This app note would be helpful to reference: https://www.ti.com/lit/an/slvafn4/slvafn4.pdf?ts=1720532530217&ref_url=https%253A%252F%252Fwww.google.com%252F

    TCA9509 + TCA9617B will be similar to the use case described in this application note. TCA9517 and TCA9617B have similar static voltage offsets on B-side. 

    Connecting the TCA9509 B-side to B-side of TCA9617B is an okay use case. 

    Regards,

    Tyler

  • 0 in reply to Tyler Townsend
    TI__Genius 11340 points

    Hi Tyler，

    Pls refer to the block diagram below. The I2C on the CPU side is powered by 3.3V, but the other devices are powered by 3.3V STBY. So basically, I need a device to isolate the 2 different power domains to avoid leakage. The problem is that the 9617s are on other boards that are already in production, and there are two different configuration.  The B side of TCA9509 would be connected to both A side or B side of TCA9617. Could you please check if this application is ok? If not, is there a replacement for 9509?

    Rregards,
    Hailiang

  • 0 in reply to Hailiang Zhang
    TI__Guru 50588 points

    Hi Hailiang,

    This is a valid connection. Either the TCA9509 can be connected with A-side facing CPU with no pull-up resistors and B-side facing 9617B's. 

    Or you can replace TCA9509DGKR with p2p TCA9617B with A-side facing the other 9617B's, and B-side facing the CPU side. However, VIL(cpu) = 0.3 x 3.3 = 0.99V for this to work. VOLB of the TCA9617B will not work for the CPU if its VIL = 0.4V. 

    Regards,

    Tyler

  • 0 in reply to Tyler Townsend
    TI__Genius 11340 points

    Hi Tyler,

    There's one more question. In the doc you sent (slvafn4), the nets between 9517 B side and 9509 B side have two PUs to VCCB. But actually, the two VCCB can be two different power rails, right? And if they are the same power rail, just one PU is needed? Thank you.

    Regards,
    Hailiang

  • +1 in reply to Hailiang Zhang
    TI__Guru 50588 points

    Hi Hailiang,

    Hailiang Zhang said:
    But actually, the two VCCB can be two different power rails, right? And if they are the same power rail, just one PU is needed? Thank you.

    You don't have to have two 1.6kohm pull-up resistors to VCCB. Only one pull-up resistor is fine. 

    In figure 2-3, VCCB should be the same for TCA9517 and TCA9509. Not two different power rails. 

    Regards,

    Tyler