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TPS61202+LM2831+LM3670:power from same input source?

eli
Guru 13485 points
Other Parts Discussed in Thread: TPS61202

2046.TINational DC-DC Array blok diagram.pdf

customer is using DC-DC Converters like TPS61202, LM3670MF-ADJ, LM3670MF with inputs connected together (see attached file).

 Please, advise if this solution looks OK. Or maybe  needed  to do something to prevent possibly  mutual interference of input circuits of the DC-DC.

  • 0
    TI__Guru**** 150770 points

    This is likely ok as each power supply IC's input cap decouples it from the input bus.  You could always order the evaluation board for each device and hook them together as shown.

    It is important to follow the datasheet recommendations regarding the external components as well as board layout.

  • 0
    TI__Intellectual 1955 points

    Hi Eli,

    Schematically your question regarding bypass cap and input connection is basically fine.  However your concerns of interference is really real if layout was not done correctly or optimally.   In these buck converters, the Power pin is very noisy due to the large current pulse ripples from switching operation.  The input bypass caps must be as short as possible that is 1 mm or 2 of PCB metal trace distance between the cap and the device Vin pin may often make a difference.  As few as 150mV of ripple may disrupt normal device operation!    The second concern is place ment of the power nets.  They should be well segregated such as using a star configuration scheme.  Distance is your best strategy for minimize mutual inductance and coupling. When issuing connection and layout information a diagramatical drawing is more helpful than a schematic representation.

    Kern