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LMR23630-Q1: Optimal placement of two DC/DC Convertors side by side

Pradeep Mohan
Intellectual 725 points
Part Number: LMR23630-Q1
Other Parts Discussed in Thread: LMR23625, LMS3655

Hello TI,

What precautions should be taken when placing two LMR23630s side by side? Do I place them orthogonal to each other or parallel? The Vin and Vout paths are similar to that in the evaluation board keeping the loop area for the high di/dt components of the pulsing current as small as possible. 

  • 0
    TI__Mastermind 49037 points
    Hi Pradeep,

    I forwarded your enquiry to the product expert.

    Regards,
    Tim
  • 0 in reply to Timothy Hegarty
    TI__Genius 11040 points
    Hello,

    One option would be to place the two ICs next to each other. This way you can have a continuous VIN plane to the input. As you mentioned the key is going to be to keep the Vin path (high di/dt loop) as small as possible to limit any parasitics.

    This reference design shows an example of two buck converters in parallel. This example is with the LMS3655, but you can also use it as an example layout for the LMR23625.

    www.ti.com/.../PMP20249

    Best Regards,
    Katelyn
  • 0 in reply to Katelyn Wiggenhorn
    Intellectual 725 points
    Hello Katelyn,

    thank you for the comprehensive reply and the example layout, that helps a lot! Please correct me if I'm wrong, but do the radiated emissions couple stronger from the two circuits if they are placed parallel to each other? Is there any advantage placing them perpendicular to each other?
  • 0 in reply to Pradeep Mohan
    TI__Genius 11040 points
    Hi,

    You are correct that you will want to keep the inductors as far as possible from each other and keep the switch node areas as small as possible.

    Second, you will want to add extra bypass capacitors at the input of each converter in order to ensure there is not increased noise at the input.

    Third, you could sync the two converters together as well to improve the emi performance.

    Please let me know if you have any additional questions.

    Best Regards,
    Katelyn