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Inexpensive DC-DC converter/SMPS design idea and suitable topologies

Tony Stewart

Well-Known Member
Most Helpful Member
Simple does not get you great specs. He must have made flybacks beforehand the chip proposed looks simple in parts yet is far from simple. Harmonic aliasing of cascaded Bucks needs careful design to avoid cross step load errors.
 
He needs simple. This project is too much for the first one. It is way beyond his skill set. One option is this circuit to make 24V and then add two simple buck circuits to get 12 and 5.
View attachment 134508View attachment 134510View attachment 134511
Hi Tony, If you want to teach him how the below circuit works go ahead. Neither of us are getting paid to teach today. Choose a simple option.
View attachment 134509

Among all lets take first one UCC28740. In post # 12, infineon solution looks expensive.
I am tryng to calculate parameters. Lets change the transformer turns ration, inductance and so on.
 

ronsimpson

Well-Known Member
Most Helpful Member
You need some tools and a chance to play with a circuit.
Here is a 400VDC to 24V isolated flyback. Not what you want but a start.
Attached is a file. Down load LTSPICE and put it on your computer. Then open my file.
You should see the schematic. Click on "run" and wait for a while. Click on the output voltage. It will take 150mS for it to start and make voltage.
This is a good place to learn how things work and what happens when changes are made.
Save the schematic to a different name before making changes so you can get back.

1637283221358.png

Red trace is the voltage on M1.
Good luck
RonSimpson
 

Attachments

  • LT8316flyback-ron.asc
    4.3 KB · Views: 5
You need some tools and a chance to play with a circuit.
Here is a 400VDC to 24V isolated flyback. Not what you want but a start.
Attached is a file. Down load LTSPICE and put it on your computer. Then open my file.
You should see the schematic. Click on "run" and wait for a while. Click on the output voltage. It will take 150mS for it to start and make voltage.
This is a good place to learn how things work and what happens when changes are made.
Save the schematic to a different name before making changes so you can get back.

View attachment 134513
Red trace is the voltage on M1.
Good luck
RonSimpson
Yes. Great!
I have LTspice in my PC.
It will be fun to play with it.
Thank you!
 

rjenkinsgb

Well-Known Member
Most Helpful Member
How did you become good engineer without homework ? Did you climb top of the tree in the first day?
Not at all - but I did not ask other people to do it for me, or create or format reports and reasoning for me:

I have no problems with questions and helping people, but doing homework for them is a step too far.
 

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