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I need some help about choosing the best on board switching power supply that has the less electrical noise and longer life time between these schematics for a 5V 200mA board...

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Heating is important too!

If any one can come up whit something better I will appreciate it!!!

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  • \$\begingroup\$ The third one is isolated and less likely to kill you. \$\endgroup\$ – markrages Oct 30 '14 at 20:02
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    \$\begingroup\$ Do you have experience with designing these types of supplies? There are a lot of dangers and also a lot of regulatory requirements (if you are trying to make a product). I would strongly encourage you to do like almost every other commercial product in the world does, and use an external brick type power supply. If you need really clean power, since you are only talking about 200 mA, you can use a 9V external supply, and put a linear regulator on your board to take it down from 9V to 5V. \$\endgroup\$ – mkeith Oct 30 '14 at 20:08
  • \$\begingroup\$ That's cool but I have to assemble it on my board, no choice here...! \$\endgroup\$ – kia_rst Oct 30 '14 at 20:11
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The 2nd one is a linear regulator. It is very inefficient, but cheap and easy to implement.

The 3rd one is good, but it involves custom transformer design. As far as I understand, you don't have knowledge in this topic. So, avoid it.

The 1st one is the one you should choose. Just choose the current rating of the inductor L1 correctly.

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  • \$\begingroup\$ Thanks...I dont know how to design a transformer but if you can help me to order it (For example: 1:10) that can be so nice and what kind of transformer should I use here?!! \$\endgroup\$ – kia_rst Oct 30 '14 at 22:22
  • \$\begingroup\$ It is not something readily available. You have to choose a core, you have to calculate optimal wire geometry, you have to bundle the wires to form Litz structure. All these require great knowledge, calculations and experience. You shouldn't involve with it at this level. \$\endgroup\$ – hkBattousai Oct 31 '14 at 3:58

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