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LMK00308: CMOS control input pins and loading effect

DEEPAK V14
Intellectual 810 points
Part Number: LMK00308


Hi,

1.Can I operate CMOS control inputs such as CLKin_SEL1 or CLKin_SEL0 or CLKoutA_TYPE0 of multiple (say 5 numbers) LMK00308SQ from a single 3.3V LVCMOS GPIO pin of KINTEX7 FPGA without any loading effect?

2.What to do with unused CLKIN and OSCIN pins. Can we leave it as unconnected or ground them?

3.What to do with unused REFOUT_EN and REFOUT pins. Can we leave it as unconnected or ground them? 

Thanks in advance
DEEPAK V

  • 0
    TI__Mastermind 32575 points

    Hello,

    1. The LVCMOS input leakage spec of 50uA max indicates input pulldown is higher than 66 kohm.  So, if there are 5 input pins driven in parallel, I think the FPGA needs to be able to drive ~10 kohm load.
    2. Unused input can be left floating.
    3. Unused outputs can be left floating.

    Regards,
    Alan