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  • TI Thinks Resolved

TCA9509: Can this be used as an I2C repeater if both supplies are 3.3V?

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Replies: 7

Views: 250

Part Number: TCA9509

Hello,

Can the TCA9509 be used as an I2C repeater if VCCA = VCCB = 3.3V?

The data sheet states that both supplies can take 3.3V, so it seems like it should work as the two maximum voltages are the same:

But further on it states: “For the level translating application, the following should be true: VCCA ≤ (VCCB – 1 V)”

I’m using this as a repeater and not a translating application.

Thanks!

  • Hey Michael,

    May I ask why you chose the TCA9509?

    If you want to use an I2C buffer at Vcc1=Vcc2 then I would probably recommend TCA9517. The TCA9509 was designed to work with VccB>VccA+1V so using it at Vcc1=Vcc2 will likely violate datasheet specs.

    Thanks,
    -Bobby
  • In reply to BOBBY:

    Hi Bobby,

    Thanks for the quick reply. My customer had already chosen TCA9509. Would the TCA9306 work? The smaller package options would be ideal.
  • In reply to Michael Balourdas:

    Hey Michael,

    "Would the TCA9306 work?"
    I want to be sure, did you mean the PCA9306 or the TCA9509? (Or our pre RTM TCA9306?)

    -Bobby
  • In reply to BOBBY:

    I did mean PCA9306, thanks for clarifying.
  • In reply to Michael Balourdas:

    Hey Michael,

    So PCA9306 is a level shifter, if you use the device to be Vcc1=Vcc2 on this device then the only thing beneficial about this is you could use the enable pin to disable it kind of like a switch.

    I need to be very clear about this, PCA9306 is not a true buffer meaning it does not redrive the signal. If the customer is trying to seperate/isolate the bus by disabling the device so keep the downstream I2C segmented from the main I2C bus then this device will work. If the I2C bus is heavily loaded and a redriver/buffer is needed then PCA9306 is not a suitable solution.

    Thanks,
    -Bobby
  • In reply to BOBBY:

    Bobby,

    Thanks for that explanation. The customer does need a true I2C buffer.

    Their specs are: 2mm x 2mm or smaller, 3.3V on both supplies, 400kHz max SCL

    Do we have anything that fits? I want to make sure I'm not missing something.

    Thanks,
    Michael
  • In reply to Michael Balourdas:

    Hey Michael,

    Could you please check your email? I've sent you a message for further details.

    Currently we do not have a solution but may put something like this in our backlog.

    Thanks,
    -Bobby

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