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AMC1210 : CLK tree

alpha
Expert 2530 points
Other Parts Discussed in Thread: AMC1210

Dear specialist

Our customer has been considering AMC1210.
Although Figure13 on datasheet describe CLK tree for each units , Filter unit and Comparator is not connected CLK.

What is source CLK for these modules?

Although customer will not use these modules , can CLK pin connected to GND?

Best regards.

  • 0
    TI__Guru**** 168605 points

    Hi alpha,

    The four filter modules use the four CLKx input pins.  This can be derived from the System Clock (CLK pin 16) or an external clock source depending on the modulator being used with the filter chip.  The system clock is still needed and cannot simply be tied to ground.

  • 0 in reply to Tom Hendrick
    Expert 2530 points

    Dear Tom

    Thank you for your quick response.

    My understanding is Control Module is deliverd from System CLK and AMC1210 can operate CLKx from external source and System CLK is async.

    Is that right?

    Best regards.

  • 0 in reply to alpha
    TI__Guru**** 168605 points

    Hi alpha,

    Yes, the system clock can be asynchronous to CLKx.  If you are using a modulator with an internal clock, you can feed that to both CLKx and CLK as well.

  • 0 in reply to Tom Hendrick
    Expert 2530 points

    Dear Tom

    If customer is using a modulator with external CLK , can customer feed external CLK to both CLKx and System CLK?

    In that case are there any concern?
     
    Best regards.

  • 0 in reply to alpha
    TI__Guru**** 168605 points

    Hi alpha,

    The four CLKx pins are bidirectional.  If you apply a clock to the CLK input (pin 16) that signal can then be driven (internally through the AMC1210) to the four CLKx pins to ensure all modulators are running synchronously to each other.

  • 0 in reply to Tom Hendrick
    Expert 2530 points

    Dear Tom


    Thank you for your reply

    Our customer will CLK input(pin16) and that will be driven to four CLKx pins.
    Although CLKx pins will be unused , how to deal with these pins?
    Can these pins left open?

    And also they will not use SH1/2 pin.
    1. How to deal with unused pins of SH1/2 pin ?
    2. Are there any concern if these pins are not used?

    Best regards.

  • 0 in reply to alpha
    TI__Guru**** 168605 points

    Hi alpha,

    Unused input pins (the S/H for example) should be terminated.  You can tie them to GND.  If all four CLKx pins are configured as outputs and some are unused, you could leave them open.  However, if you do not need all four CLKx pins, just configure the ones you do need and terminate those which are unused.

  • 0 in reply to Tom Hendrick
    Expert 2530 points


    Dear Tom

    Our customer has one more question.
    If customer are using internal CLK that is driven to the four CLKx , are there any concern ?
    What they concern is whether CLKx output mode affect to analog circuit(eg. noise due to CLKx output).

    Best regards.

  • 0 in reply to alpha
    TI__Guru**** 168605 points

    Hi alpha,

    I cannot think of any problems you might encounter. 

  • 0 in reply to Tom Hendrick
    Intellectual 855 points

    Dear Tom,

    Regarding to configure CLKx direction, the bit CD in the control parameter register needs to be set to "1", alowing the CLKx pin to become an output. Is it right?

    If I want to configure only two CLKx pins to become an output, what shall I do? I cannot find how to configure those setting on the datasheet.

  • 0 in reply to avraka
    TI__Guru**** 168605 points

    Hi avraka,

    The direction of the CLKx is configured in the Control Parameter Registers, Bit 4.  When 'set', CLKx is an output - when cleared (default state), its an input.  Each filter has it's own CP register (addresses 0x01, 0x07, 0x0D and 0x13).  All you need to do is set the bits in the registers for the filters you wish to use.