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Actually I'm using a simply switching buck regulator that perform a 24v to 12v convention. I'd like to add isolation between power source and regulator. I've checked already all-in-one isolating DC-DC converters, but they are expensive and have low current supply (about 200mA , actually I've 800mA-1.0A peaks) with low input range, where at about 26V they fries.

Another application that I've found are DCM Fly Back ICs coupled with common inductors. Like LT8301/2, but they are also very expensive ICs with also 400mA limitation at 12V.

Are there inexpensive solutions to add an isolation between DC power supply source and my DC regulator?

Is it possible, something simple, like to put a 1:1 DC:DC coupled inductor between 24V and DC buck regulator?

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  • \$\begingroup\$ Why not ditch the DC regulator and use a flyback design that does 12 volts at 1 or more amps from 24 volts? \$\endgroup\$
    – Andy aka
    Apr 10, 2020 at 13:13
  • \$\begingroup\$ I've found a lot a fly back designs with several ICs with high prices. I didn't found any low cost IC design (a single at about 5 to 8 euro just controller IC like from LT in my question). Maybe there's simpler a lower cost solution that I don't know? \$\endgroup\$
    – Singed
    Apr 10, 2020 at 13:18
  • \$\begingroup\$ Flyback is the most common way to make a small 1 to 50W isolated supply... You can find IC chips as cheap as 1.5USD. and for your type of voltage conversion, you can use an off the shelf transformer... Otherwise 1:1 isolation supply's are common and available for ~10USD for like 5W of power. \$\endgroup\$
    – MadHatter
    Apr 10, 2020 at 13:52
  • \$\begingroup\$ Use a site like digikey and filter. \$\endgroup\$
    – MadHatter
    Apr 10, 2020 at 13:54
  • \$\begingroup\$ also I should note part of the reason why isolation supplies are not necessarily found to cheaply, is because most of them are certified for safety with government agencies. Anything that comes with a certification is going to come with a cost. \$\endgroup\$
    – MadHatter
    Apr 10, 2020 at 14:32

1 Answer 1

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Given your application, you need ~5-10W of isolated 12V power from a 24V source. There are two common options available:

  1. Use an off the shelf 1:1 isolation DC/DC supply. You could go from 24V to 24V, and buck etc. afterwards. As for price, they run 10-20 USD. Here is one that exactly works for you, even allows 18-75V input and outputs 24V 6W for 10USD. 1866-4815-ND
  2. Flyback supplies (DCM or CCM) are the ideal supply for this option. If this is a 1 off project, it could be a good learning experience, but it will be more work vs using an off the shelf module like #1. There are plenty of cheap IC chips, and for your 24:12V you can buy an off the shelf 1:1 or 2:1 transformer. Here is a 1.5USD IC that has built in transistor etc. CS5173GDR8GOSCT-ND

Goodluck! Use Digikey next time.

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