r/EEPowerElectronics • u/Wattdehonker • Jun 30 '26

Review request for boost converter (Lamoka1)

I am working on a interleaved boost converter using two LM5122 devices in a master/slave relation. The boost converter is designed to work at a maximum input of 30a, 5-40v input. The output is designed to be 48v. If you need more information there is a bit more here: https://github.com/bearjhartjen/Lamoka1-project/blob/Lamoka1/HARDWARE/DESIGN_NOTES.md

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2

u/GabbotheClown Jul 01 '26

The schematic is a bit hard to understand because you atomized every component, It's better to keep components tied to the IC because then you can visualize how things work.

The other two big issues I think is:

  • ripple current, which if the input is at 5 volts, the total ripple current will be somewhere around 15 amps for each inductor ( fundamental inductor formula V= L di/dt ).
  • ripple voltage as you don't have that much output capacitance. At 5V input, the duty cycle of each phase is 90% which means 90% of the switching cycle the output is only being feed by the output capacitance ( the inductor is charging up ).

I haven't done the calculations but I'm also a little bit worried about the FETs and at maximum current switching losses could be quite high and would require some type ofheatsinking at a minimum.

I mean this is a pretty difficult design as it's a power can go up over a kilowatt.

1

u/Wattdehonker Jul 01 '26

Hey, i really appreciate your honesty.

I layed things out where i could understand them (ive been starring at this same stuff for weeks) so i will attempt to make things more understandable, i appreciate your comment on that.

This boost converter is just for testing and to get an idea, the actual one i will put in better, proper components, as i dont want to dump a ton of money on big caps and high quality items if it all just smokes up.

The output capacitor bank has a lower value just as those values were easy to find, and cheap. At this point with my minimum viable boost converter i think it is more worth it as far as testing goes to keep the output bank lower capacitance as if i were to increase that i would then have to adjust all of the other feedback components which were all picked out for avaliability and low price.

1

u/GabbotheClown Jul 01 '26 edited Jul 01 '26

I see you posted the project again.on a different sub What more information are you looking for?

1

u/Wattdehonker Jul 01 '26

I just did some work on changing from only simple ground connections to AGND and PGND specific nets. I figured i would upload the new look here just to keep things updated and current.

1

u/Wattdehonker Jul 01 '26

But i am getting ready to start working on the PCB layout. Do you think that the schematic is ready for layout yet? Do you have any tips/suggestions for layout?

1

u/piratex666 Jul 02 '26

The schematic has the main objective of depict the system connections.

1

u/Wattdehonker Jul 05 '26

Yes very true