LM2576 PCB design question

[giszo]

Hello!

I am designing a PCB for my project and planning to use the LM2576 for voltage regulation. I have never worked with this IC before and would like to receive some input on my PCB design whether it's good for this switching regulator, or something should be adjusted to achieve better results.

Here is my current PCB design (regarding the regulator):
**broken link removed**

Any help would be appreciated!

giszo

 

[Easyrider83]

For hand-made soldering good. Difficult to solder C2 when L1 is placed. And C1 is too close to board edge, C1 label is out. Mounting pads (green) should be connected to ground I suppose? And try to place all heating elements closer to board center where it can heat the board to all directions.

 

[giszo]

I could move C2 a bit towards the right side of the PCB but in that case it gets closer to the heat of the LM.

Moving everything down by a step or two will create more space for C1 to the board edge and L1 will still have enough clearance to the mounting hole. The label of C1 doesn't really matter as this will be a home-made PCB without printed labels.

Maybe it's a bit off-topic here but how much heat the LM will generate while regulating 12-14V down to 5V @ 1A?

 

[FvM]

Maybe it's a bit off-topic here but how much heat the LM will generate while regulating 12-14V down to 5V @ 1A?

Did you motice the efficiency graph in the datasheet? I would expect 1.3 to 1.5 W power disspation for LM2576 and schottky diode according to it, probably at least half of it in the diode.

I fear that the diode connected copper pours might be too small, it's also no good idea to apply thermal relief for components with heat dissipation.

 

[giszo]

I've seen the datasheet and I know this regulator is much better (in efficiency) compared to a well known linear regulator. Unfortunately I have no experience with this one at all, so I had no clue about dissipation, etc.

I'll remove the thermal relief from the LM IC and the diode.

Two more questions:
- should I use thicker lines in LM->D1 and D1->L1 lines?
- should I make more space around D1 to allow better cooling?

 

[FvM]

For better cooling, D1 should have larger copper pours around both pads, at least one of it.

 

[giszo]

Thanks to both of you for the help!

I have made these modifications on the PCB plan, and I hope it will be better now. ;-)