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| Design ideas for a low-count part, low power isolated DC-DC power supply? |
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| 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. |
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