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TCA9548A: I2C-Mux -Q or not Q

Marks Greulich
Intellectual 540 points
Part Number: TCA9548A
Other Parts Discussed in Thread: PCA9518

Hi there,

I already designed in the TCA9548ARGER on our boards. 

There is a Version -Q available but we are a bit confused because the Q-Version is rated only to 85deg. The other ones (depending on VCC) up to 125°C. Why is the Q specified lower? 

Thanks and best regards,

Markus

  • 0
    TI__Guru 72751 points

    Hi Markus,

    The commercial device was tested and re-qualified for a higher temperature while the automotive was not (this was done AFTER the automotive version was released). While the internal dies are likely very similar to each other, some of the other material in the packaging may not be, so we were not allowed to modify the automotive datasheet to have the same limits as the commercial. 

    -Bobby

  • 0
    Intellectual 540 points

    Hi Bobby,

    thanks for your feedback! So I have to get the commercial one with the higher rating. 


    Second question is: this I2C-Switch, is it just passive without any kind of signal "refreshing"?
    Meaning lets say a 5V I2C signal is going into the IC from master side and going out as a 1.8V signal to the slaves. Lets say if the edges or the signal is weak cause of whatever reasons from the master side (e.g. a long trace before) is the the output signal freshed up with steep edges etc.? 

    Thats what I have not understood how it works. 

    If that is not the case - any ideas which parts I can use to buffer/refresh a long I2C-Trace to get again better signals?

    Thanks,

    Markus

  • 0 in reply to Marks Greulich
    Guru 316690 points

    The TCA9548A is a passive switch, so the signals are not improved.

    The PCA9518 is a buffer that can switch four slave buses.