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CDCE706: Using the same bus with two devices and the CLK_SEL input

Stefano Infante
Expert 2310 points
Part Number: CDCE706

Hi all!

On my device I need to use two CDCE706; on both of them I need the CLK_SEL input as I have two different clock and I must allow the user to choose the one he wants to use.

I see that the S1/A1 input can be used as a SMBus device address, so I think I could connect both CDCE706 to the same bus and use that pin as a "device select".

But it is not clear to me whether the CLK_SEL function on S0 and address function on S1 can be used together at the same time. Can you please clarify?

Thanks in advance.

Best regards,

Stefano Infante

  • 0
    TI__Intellectual 950 points

    Hi Stefano,

    Let me run this question by some other members of my team in order to verify that I'm providing you the proper information. I'll have an update for you by next Tuesday.

    Regards,

    Adam

  • 0 in reply to Adam Siismets
    TI__Intellectual 950 points

    Hello Stefano,

    If I understand your question correctly, you're wondering if the S0 and S1 pins can be used as both control pins as well as address pins at the same time? 

    If that's the case, then no you cannot. If you look at the section of the datasheet titled "Multifunction Control Inputs S0 and S1" on page 28, you can see that it says:

    "The CDCE706 features two user-definable input pins which can be used as external control pins or address pins."


    Depending on how you program byte 10 and drive the external control pins, you can have the part operate in different ways, but each of these modes is discrete and cannot operate at the same time as another.

    Also for the record, you can have up to four CDCE706 parts on the same SMBus so having two will not be a problem.

    Hope this helped,

    Adam

  • 0 in reply to Adam Siismets
    Expert 2310 points

    Hi Adam,

    but if I use both signals as address lines, how can I select the input clock?

    Thanks,

    Stefano

  • 0 in reply to Stefano Infante
    TI__Intellectual 950 points

    Stefano,

    You can still select the input clock through programming a register if you're using the pins to set the address.

    Adam