LTC3633A output coupling switching noise

Hi all,

Our customer will be going to select power IC, mult ch output.
They will be concerned the output coupling, and switching noise.

In the datasheet LTC3633A, page 12 "OPERATION" say following.
"One potential disadvantage to this configuration occurs when one channel is operating at 50% duty cycle.
In this situation, switching noise can potentially couple from one channel to the other, resulting in frequency jitter on one or both channels.
This effect can be mitigated with a well designed board layout."

Why occur to couple at 50% duty cycle ?
, and the condition is 50% duty cycle only ?

Best regards,
sss

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  • 0
    •  Analog Employees 
    on Mar 1, 2018 11:34 PM

    Cross-talk can be mitigated by placing the input cap close to the LTC3633A, and the output cap close to the inductor.  You can find layout recommendations on pg 21 and pg 23 of the datasheet.

    Typical performance data is not very useful in this scenario as it depends heavily on layout and configuration.  With separate outputs, the risk of output coupling is low, especially since the different SW pins are on opposite sides of the package.

Reply
  • 0
    •  Analog Employees 
    on Mar 1, 2018 11:34 PM

    Cross-talk can be mitigated by placing the input cap close to the LTC3633A, and the output cap close to the inductor.  You can find layout recommendations on pg 21 and pg 23 of the datasheet.

    Typical performance data is not very useful in this scenario as it depends heavily on layout and configuration.  With separate outputs, the risk of output coupling is low, especially since the different SW pins are on opposite sides of the package.

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