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Isolated 5V 5-10ma supply

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ali_asadzadeh:

--- Quote ---Chinese UU9.8 common mode filters seem to get close to that.
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Do you have any link?

Marco:
On phone now and not too going to look for it, but yesterday I saw an ebay offer for 100 pcs for 13$.

These should be able to work at relatively low frequencies.

Gyro:

--- Quote from: rvalente on December 10, 2019, 12:10:48 am ---This is siemens S7 1200 RS485 board, you can see their aproach using the MAX253 to drive the trafo.

You coud do something similar, with multiple winding in the secondary. Lets say 4 outputs per trafo.



https://datasheets.maximintegrated.com/en/ds/MAX253.pdf


--- Quote from: David Hess on December 09, 2019, 02:45:53 am ---
--- Quote from: ali_asadzadeh on December 08, 2019, 06:11:31 am ---The transformer will be the difficult part.  Gate drive and pulse transformers are suitable if you want to get something from Coilcraft or someone to experiment with.


--- End quote ---

Using pulse transformers would be very elegant design, since some of them are 1:1

--- End quote ---

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The MAX253 is a very handy little chip for such applications. It's also that rarest of beasts, a Maxim chip that has been around for at least 20 years!  ;D

ali_asadzadeh:
I have done it! and it's working better than expected for the first try! the efficiency is around 50-60%, the output with no load is around 12V and with a 7ma load, it would drop to 7V, so Now I should find a cheap SOT23-6 LDO that would generate 5V and could accept input up to 20V, and a working temp of -40~85C

The whole thing cost is under 0.5USD in single unit QTY ;)



The bonus point for this circuit is, that I have another none isolated boosted output too! so I have 4 separate isolated outputs and a single none-isolated output ;)

Marco:
Here's the ebay listing for the common mode chokes.

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