| Electronics > Projects, Designs, and Technical Stuff |
| Does this switch mode buck convertor design look OK? |
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| mosafet:
I'm playing around with a switch mode power supply design. This is just experimentation on my part nothing important. I'm just learning electronics. Does this design look OK? I'm about to etch a PCB for it. It uses a STM32 for as the driver. Yes, I know a dedicated SMPS chip would work easier/better but I love my software and microcontrollers. I currently have it running open-loop on a breadboard and it seems to work. I didn't have room to hook up the SENSE yet. Only problem I ran across is once I accidentally reset the MCU while it was running driving a 1K ohm load and I heard a "snap" (ie. something may have arced). No damage that I could find. What could have caused that? I believe the driver MOSFET went from 50% duty at 500kHz to either solid off or on when the MCU reset. I think it turned the MOSFET on solid 100% (in theory that was OK though). Edit: to attach larger schematic picture. Change subject from SMPS to "buck converter" :P |
| ogden:
--- Quote from: mosafet on January 19, 2019, 11:32:41 pm ---I'm playing around with a switch mode power supply design. This is just experimentation on my part nothing important. I'm just learning electronics. Does this design look OK? --- End quote --- No. It has many problems. Sorry, but SMPS *design* is one of the worst possible projects for beginner. Either 1:1 copy some proven design (including PCB) or reconsider your project completely. You may want to read ST application note AN4449. Also you may want to just buy STM32F334 Discovery kit, play with it first. |
| mosafet:
--- Quote from: ogden on January 20, 2019, 12:04:58 am ---No. It has many problems. Sorry, but SMPS *design* is one of the worst possible projects for beginner. Either 1:1 copy some proven design (including PCB) or reconsider your project completely. You may want to read ST application note AN4449. Also you may want to just buy STM32F334 Discovery kit, play with it first. --- End quote --- I forgot to mention that I build everything from scrap parts so buying stuff is more of a long term goal when I have money. Just saying "many problems" is not very helpful. What problems? I read the note and I don't see the problems. I don't need boost, only buck and my circuit is similar. This isn't powering a heart monitor... :-// I always learn this way. If you tackle something hard you gain much more in my experience. Sometimes you have to blow stuff up to learn. I'm careful to not do anything dangerous to myself. Parts on the other hand, not so much. :) I already designed and have running a separate boost converter to boost 5V to 500V and I weld with it... |
| Doctorandus_P:
Your schematic is posted in a too low resolutioin and I won't bother looking at it closely. A few things I can say though: If you want to build your SMPS properly and do the algorithms in software, then put a decent MOSfet driver chip between the uC and the FET. There are also a multitude of SMPS supplys available from Ali / Ebay / Banggood / China / Etc nowadays for low prices. It's hard to beat those with a home built design. For example take the USD 25 DPS5005, which delivers up to 50V and 5A. It's also got an STM32 in it, and if you want to toy with software you can have a look at the opendps project, which is on github as an alternative firmware for this thing. |
| ogden:
--- Quote from: mosafet on January 20, 2019, 12:32:54 am ---Just saying "many problems" is not very helpful. What problems? --- End quote --- You have problem with converter topology and mosfet driver, not to mention missing capacitor after rectifier. This is buck converter, not what you are "designing": https://en.wikipedia.org/wiki/Buck_converter |
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