Electronic – Critique of SMPS layout

layoutswitch-mode-power-supply

Can you guys provide some feedback on my layout for this TP562200 buck regulator? I'm using it to take a ~12V and drive a servo. The supplied resistor values should provide about 5.1V, which is within the range of what the servos want. This will be used on a board that's got some sensitive components (GPS, sensors, etc.), and controlled by an ATMega2560. I'm only turning the regulator on when I need to drive the servos (which is typically a few times per minute).

I've tried to follow their reference design and reference layout (pages 13 and 21 respectively). I'm including them here for convenience:

enter image description here

enter image description here

One thing that confused me is that their reference design includes two input caps and two output caps, while their reference layout has 1 of each. I opted for the former.

My schematic:

enter image description here

My layout. The plane on the top left is V_OUT, top right is V_BATT, and top center is ground. The bottom layer is ground as well. The trace coming in from the left is the EN signal.

enter image description here

One thing that worries me a little is that they're recommending a 4-layer design, and that's not an option for me (hobbyist level resources, both for layout and manufacture). How does that impact the layout consideration for the trace connecting the boost cap and the SW node?

Best Answer

I've looked at it for 10 minutes, and it doesn't look too bad. It's good that there is a recommended layout and you've found it.

  • Put C32 vertically between C18 and the regulator.
  • I would put the the feedback network above the regulator, rather than below. it would be shorter. Also, you'll have easier time keeping it in the top layer. (Recommended layout diagram has the feedback network routed above the controller too.)