Connect multiple vias to ground pour. Heat transfer vs. ground loops?

Thanks Paul! For you patience too :wink: I was just looking for help with a question about PCB design and got extra help with circuit design. I put the cart before the horse.

I just settled now on specs for the person who sent me this based on their need. If I limit it to 250mA, then I can power 12 to 15 LEDS or 3 60mA bulbs (Only the 60mA seem to be available).

I see the need of the capacitor at the input to the regulator too, though the extra size may be a factor. at 8kHz and 1A or less, 470uF should be enough.

Based on everyone’s input, I started on this just to compare different ways of doing things and what the cost to produce each board would be. This one is about $2-$3 before the cost of the PCB. I want to do all the proper math and model it in LTSpice. I guess I only need one big capacitor as a filter because it can just power the switching power supply until it drops out and use a smaller cap at the output of the regulator? I also am looking at the LM2596 or the MP2307, as possible chips to design around, but there is a lot of study to do.

That’ll work. Be sure to use MLCC surface mount capacitor as C2, another MLCC surface mount capacitor at VOUT (not in your schematic), and closely follow the recommended layout in the datasheet. The thing switches in the MHz range and a good layout ensures stability and low noise.

By the way the 1,000uf cap can go before the regulator instead, and the value could most likely be smaller. This is because at much higher efficiency, the switching regulator draws a much lower current than would a linear regulator. At steady input state (e.g.16V), the input current would be less than 1/3 the load current. Besides, this can eliminate the “brown-out” effect during DCC drop-out, as the switching regulator works over a wide range of input voltage. However, if you decide to do that (putting 1,000uF right after the rectifier bridge), you may want to put a resistor, say 10-ohm, in series between J1 and D1, to limit the inrush current impact to the DCC line.

p.s. I’m afraid the MBL series rectifier bridges are designed for 50/60Hz sinewave, may not suitable for 8/4KHz fast switching square wave applications. If concerned, CD-HD201 can be a Schottky alternative.

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This is exactly what i do except i use thermal vias only around component and dont propagate them outward too much since it is not really necessary in my case where i have board in the same environment (in case you use board as case and there is considerable temperature or air flow difference between board sides then it makes more sense)… Also sometimes i use flat board to connect to heatsink via thermal block and some silpad, it reduced temperature of the components

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