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TCA9544A: four master to switch one device

Shu-Cheng LIN
Guru 11785 points

Part Number: TCA9544A
Other Parts Discussed in Thread: TCA9546A

Hi Sirs,

As title,

We know TCA9544A could use one master to switch four device.

So, how about to use on four master to switch one device? 

Have any risk?

  • 0
    TI__Guru 74302 points

    Shu-Cheng,

    Please follow this thread for the answer.

    Regards,

  • 0 in reply to Eric Hackett
    Guru 11785 points

    Hi Sirs,

    Thanks for your reply.

    Our application as below

    We still have some question for use  4:1 mux

    1. May i know what different between MUX/SWITCH? because we saw TCA9544A is switch but TCA9546A is mux.

    Actually we saw NXP had 2 to 1 MUX(PCA9541APW), but if we use PCA9541 that will need 3 pcs on our board.

    2. We don't clear on your explain from. If we use Master 4 to 1 device, the master side didn't have INT pin. So how could we control?

    3. The channel looks control by Master side?? or device side could control either?

    Thanks!!

  • 0 in reply to Shu-Cheng LIN
    Guru 11785 points
    Hi Sirs,
    Sorry for pushed, have any feedback on my update?
    Thanks!!
  • 0 in reply to Shu-Cheng LIN
    TI__Guru* 78861 points
    Hey Shu,

    I believe Eric is on vacation due to the Holidays here in the US.

    I will take over this thread and help you while Eric is away. (Sorry for the delay until now as I have been off until today.)

    "1. May i know what different between MUX/SWITCH? because we saw TCA9544A is switch but TCA9546A is mux."
    This is actually a very important difference and I am glad you asked/noticed. A MUX can only turn on ONE channel at a time. While a switch can enable MULTIPLE channels at the same time. So a switch can be a MUX but a MUX cannot be a switch.

    Does this make sense?

    "2. If we use Master 4 to 1 device, the master side didn't have INT pin. So how could we control?"
    I am not sure I follow. Are you saying the master does not have a GPI to see an INT?

    "3. The channel looks control by Master side?? or device side could control either?"
    In your picture, the I2C master on the server side can always control the bus because he is on the main SDA/SCL channel. The other two masters I see seem to be on the other channels of the switch/MUX. This means the master on the extra channels can only control the bus when the channels are enabled.

    If this is still not clear, let me know.

    Thanks,
    -Bobby