PCB layout review of DPA 424 based power supply

Posted by: sachindevassy on 07/25/2024

Dear All,

I am making a DC-DC Converter for auxiliary power supply application. The input is 40-58V. The outputs are 18V,0.3A and 12V,1.5A. The initial design I got through PI designer, Based on available components, I made few changes. Can you please review the layout if its acceptable both functionally and as per general safety/emi requirements.

Files

18V_12V_SUPPLY_DPA424_DRAFT_schematic.pdf

18V_12V_SUPPLY_DPA424_DRAFT.pdf

Comments

Hi sachindevassy,

I found two area of concern regarding the layout

Creepage between your primary and secondary. Kindly check the encircled section of concern1.jpg. Upon computation based on your working voltage, you need at least 1.2mm or 48.5 mils of creepage. You can see in the image that R33 and R32 is near the copper path that goes into the reference pin of U3.
Kindly directly connect the nodes connected to the positive of the filter capacitor. This will reduce the EMI due to minimizing the loop area. Do the same to D3, C10, and L1. This is crucial to avoid ground loops that can cause noise in the circuit.

Aside from this, I don't see any more concern as all the signal components are near the IC. The primary and bias loop is tight and have a small area. No high dv/dt components are near the controller or a path that can introduce crosstalk to each other.

Regards

Attachment	Size
Concern 1.jpg	67.51 KB
Concern2.jpg	52.01 KB

Thanks PI-Book of Pi for your comments. I will make changes as per your suggestion.