| Electronics > Projects, Designs, and Technical Stuff |
| Layout review for buck-converter power supply |
| (1/4) > >> |
| LoveLaika:
I mentioned in previous posts that I'm building a positive and negative power supply, and the fruits of my labour are almost at hand. After going through the circuit again, I ran some more simulations and (hopefully) things look pretty good. I managed to get a layout going, but I wanted to ask if I could get a roasting (feedback) on my layout. I started out with just a 4 inch by 4 inch plane, and then I thought to move things in closer as I worked on the design. This is the result for now. It's a 2-layer board with ground planes on the top and bottom. I was thinking of just having bottom layer be ground, but since the positive regulator has its tab to ground, I thought it would be better for overall performance if the top was ground as well. I tried following TI's guide about laying out buck converters, so I kept the catch diodes, inductor, and capacitor close together, but I'm a bit worried about the feedback trace length for the positive regulator. For the input power, I plan to use posts so I can just stick some banana plug cables into it and power it from a bench supply. I haven't got to the output connectors yet, but how does it look so far? :phew: |
| thm_w:
Positive supply: Put some ground vias on the left and right of U2 and near D2. C11, C12 position could be optimized possibly. Feedback path can be optimized: take from C13, thin trace running back to R4/Rv2. But generally it looks good and you don't have to mess with those last two if you don't want to. Stitch vias are easy to add. |
| LoveLaika:
Thanks for your reply. Yeah, I really should put come ground vias to connect the two planes together. Thanks for reminding me of that. There's so much empty space, so I'm trying to move some small stuff around in order to reduce the space, and therefore the cost of the PCB boards. Regarding the feedback path, the issue I have right now is that it starts at one end of the inductor, PCSP, and it has to connect to pin 6 of the IC. The pin placements are rather difficult to route without putting the components closer. How would you recommend routing it from C13? I'd have to move it around, but right now, it's still hanging at the top left unless I re-orient the inductor. Regarding C12, I can move it , but as long as it's connected properly, the sense resistor can just connect to C10 instead of C12, correct? The two caps are parallel, so as long as they are connected at the same node, I can put C12 across from C10 and move the components closer together to save space. |
| free_electron:
ehh . where is the current regulation loop ? you have a limit detector , but you don't use it to fold back the output voltage... |
| Jay_Diddy_B:
Further to the comment from free_electron. The way the circuit is drawn, you have LEDs that come on if a current threshold, set by a potentiometer is exceeded. The circuit does not limit the current. In addition the threshold for the negative circuit is proportional to the negative voltage. The higher the negative output voltage the higher the current limit. Regards, Jay_Diddy_B |
| Navigation |
| Message Index |
| Next page |