Electronics > Projects, Designs, and Technical Stuff
Design ideas for a low-count part, low power isolated DC-DC power supply?
<< < (4/10) > >>
Marco:

--- Quote from: SiliconWizard on November 07, 2018, 12:27:55 am ---I'm currently simulating a simple solution which bears similarities with this: https://www.maximintegrated.com/en/app-notes/index.mvp/id/4553 , only I just use 2 diodes instead of a full bridge, which is fine for what I need (and has lower loss), and no specific h-bridge IC.

--- End quote ---
Simulate what happens if you ground both sides, I think it goes wonky.
SiliconWizard:

--- Quote from: Marco on November 07, 2018, 12:43:52 am ---
--- Quote from: SiliconWizard on November 07, 2018, 12:27:55 am ---I'm currently simulating a simple solution which bears similarities with this: https://www.maximintegrated.com/en/app-notes/index.mvp/id/4553 , only I just use 2 diodes instead of a full bridge, which is fine for what I need (and has lower loss), and no specific h-bridge IC.

--- End quote ---
Simulate what happens if you ground both sides, I think it goes wonky.

--- End quote ---

I just tried. It changes efficiency a bit, and I get a slightly higher output voltage (which I would have expected) but still works fine.
Will post a schematic shortly.

Note: I'm not using an h-bridge topology. If I did, obviously grounding the "isolated ground" would short-circuit one of the H-bridge outputs. It would not like that.
Marco:
I think it essentially shorts out one of the capacitors, there's still no DC path, but the fact that it changes the output voltage is a bit annoying.
SiliconWizard:

--- Quote from: Marco on November 07, 2018, 12:56:23 am ---I think it essentially shorts out one of the capacitors, there's still no DC path, but the fact that it changes the output voltage is a bit annoying.

--- End quote ---

I don't mind. And this should be a degenerate case, as you'd obviously lose the isolation - I only expect the system not to be destroyed by it.

You nailed an important factor though, as if using an H-bridge as suggested in Maxim's note, this would lead to a short-circuit of one of its outputs. If it's protected against short-circuits, fine, but if not...
Marco:
It doesn't really short it ... it just makes the MOSFET burn all the energy put into one of the coupling the capacitor each cycle, which creates a limited amount of power, but still too high for comfort.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod