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Original question:

TPS54394: Problems with SW signal in regulator. Final ripple too high at the output.

TPS54394: Power management forum

Tony Karavidas
Prodigy 215 points
Part Number: TPS54394

It's funny on one thread regarding this part, someone said the user's layout was very bad because the switch node was connected to the inductor using a different layer. That is the (poorly) recommended layout on page 16 of the data sheet. Maybe TI should update that to offer better advice to newbies

Here is the thread I'm referencing: (1) TPS54394: Problems with SW signal in regulator. Final ripple too high at the output. - Power management forum - Power management - TI E2E support forums

  • 0
    TI__Mastermind 22340 points

    Hi Tony,

    Thanks for your useful suggestion. We will check internally soon.

    BRs

    Lucia

  • 0
    TI__Mastermind 24890 points

    Hi Tony,

    Thanks for the feedback. There is a special consideration when the SW node is between the VIN and GND pins like in this case. This app note (see figure 7) suggests routing the SW connection underneath the input capacitors which must be placed close to the VIN and GND pins. This is probably the best option here and we will discuss internally on datasheet updates regarding this. The other alternative mentioned is using vias to connect SW pin to inductor similar to what datasheet suggests but it does tend to increase EMI due to longer routing. The issue on the ripple could be related to the layout when the current is higher or it could also be related to input cap placement - I do not see the final feedback from the customer after making the recommended updates. Thanks again for your feedback and please let us know if you have any more questions.

    Thanks,
    Amod