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I2C interface questions

Tim Baker
Intellectual 540 points
Other Parts Discussed in Thread: TCA9509, TCA9406

Hi,

When comparing I2C interfaces devices, I see no clear difference between

1.    Hubs, Translator Buffers and Repeaters; example: TCA9509

2.    I2C Translator; example: TCA9406

In I2C Guide, between the (1) TCA9509 and (2) TCA9406, the only difference seems to be that in (1), SCLA is bi-directional. All others are the same.

And since both have enable pin (1)EN and (2)OE, the claimed advantage of (1) actually also exists in (2).

And regarding the name for (1):

1.    Hub

2.    Buffer

3.    Repeater

I don't quite understand the meaning of each, and it seems that these three terms are somehow piled together. Could anyone explain the distinctiveness of each of them?

 

Tim Baker

  • 0
    TI__Intellectual 1930 points

    Tim,

    Buffer and repeater are essentially the same thing.. they receive and input signal and repeat that signal on the output with an increased drive strength.

    some buffers like the TCA9509 are level translating buffers i.e. they buffer the input signal but also translate the voltage levels.

    There are however some level translators that donot buffer the input signal but only perform level translation e.g. TCA9406.

    All I2C buffers/repeaters/leveltranslators are bidirectional.

     

  • 0 in reply to Akhil Nair
    Intellectual 540 points

    Akhil,

    Thanks for the explanation.

    There is still another word "Hub", is it also the synonym here? Hub = Buffer = Repeater?

     

    Tim

  • 0 in reply to Tim Baker
    TI__Intellectual 1930 points

    Generally speaking, a HUB is is a buffering 1:2 or more multiplexer. Strictly speaking, we don't really have a hub in our portfolio. the closest we have to a hub is a PCA9544 which is a 1:4 I2C multiplexer.

  • 0 in reply to Akhil Nair
    Intellectual 370 points

    Dear sir,

     

    I also have a question needing consult with you. Generally, lots of I2C slaves can be connected to one I2C bus at the same time.Why we need a hub like PCA9544 . It is just used to protecting the device from address conflict,is it right?

     

    Thanks!

    Michael