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TPS562201: Layout question

Zhihong Huang
Intellectual 1550 points
Part Number: TPS562201

Hi team,

After I saw the layout guidelines in the TPS562201, there are some questions.

  1. The Via for the input capacitor and output capacitor is due to the thermal problem, do I understand correctly?

  2. Why can’t the switching current to flow under the device?

  3. Why the separate path should be connected to the upper feedback resistor?

  4. What’s the Kelvin connection? Why should make a Kelvin connection to the GND pin for the feedback path?

Best Regards,

Wesley Huang 

Email: wesley-huang@ti.com

  • 0
    TI__Genius 10070 points

    Hi,

    1. The via is used for thermal performance and connect GND with bottom layer.

    2. The trace is close to FB pin and the switching noise is easy to be introduced to FB pin, this may lead to unstable.

    3. I think it means don't put the feedback point to the inductor side. To increasing the output voltage accuracy.

    4. Kelvin connection means put the feedback point close to the point which is connect to the load, to make sure the voltage of this point is more accurate. Or there is voltage drop of the PCB resistance, and the real voltage which power for the load circuit is lower.

    Shawn

  • 0 in reply to Shawn Nie
    TI__Intellectual 1550 points

    Hi Shawn,

    Thanks for your reply.

    1.From the layout in EVM-715, I see the wire between the R3 and Vout is too long, which will create the voltage drop in the FB and Vout, and it  is not compatible with your saying and layout guide. Do I understand right?

    2. could you please explain simply about the Kelvin connection?

    Best Regards,

    Wesley Huang 

    Email: wesley-huang@ti.com

  • 0 in reply to Zhihong Huang
    TI__Genius 10070 points

    Hi,

    1. You should check the Vout feedback point, not R3. 

    2. A Kelvin connection is a means of making precision electrical potential contact with a current carrying component or reference point in such a way that eliminates or greatly reduces the effect of contact resistance. For more information, you can search"Kelvin connection" on the Internet.

    Shawn