Hi,
I'm designing a 24V - 3.3V@2A DC/DC converter. I'm using LM3152 to control 2 CSD19533 in a synchronous buck topology. I'm using a 4 layer board. The thickness of the copper is 35 um (70um after plating) The "thermal pad" is connected to the drain of the device.
How should I make the thermal pads? I'm thinking of making a a copper pour around 3 cm x 3 cm on bot(4) and top (1) layer and connect them with many vias. The component is located on top layer. Should I make extra clearance for the thermal vias on 3.3V (3) and GND layers(2) (maybe remove the copper in between the thermal pads all together). My main goals are minimise ringing and noise and lower the operating temperature as much as possible.
Does the size of the thermal pads effect the ringing and noise of the converter? Eg if I made a large bottom pad (5x5 cm or larger).
I have look at some of the application notes but I mostly find how to place the components or how to make thermal pads for ICs that have the thermal pad connected to GND. If there is a example of how I should do this please link it.
Best regards,
Marko