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Original question:

LMK00301: Unused output

LMK00301: Unused output pin

Lacey Lin
Intellectual 2900 points
Part Number: LMK00301

Hi team，

For the unused pin, we recommend to left floating.

Customer want to know the risk for the pin to become a antenna then to couple with other outputs.

In their application, the input and output are all 245.76M, they use 4 outputs in each bank. So there is one output in each bank left to be floating.

So please help to give the reason why this floating pin will not affect other outputs.

Lacey

Thanks a lot!

  • 0
    TI__Guru** 108550 points
    Hi Lacey,

    When you left the unused pins floating, the load impedance to the drivers is infinite high. As such, the driver drawn very few current. Any crosstalk that is coming from the power supply path become minimal.
    Furthermore, the physical size of the pcb pads for the unused pins are very small, radiation is virtually not possible. FYI, a quarter-wave antenna at this frequency is approximate 30cm long.