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The Magic Demystified- How SMPS and Boost Power Supplies Work.

🕑 Added 2019-08-19 22:17:03 +0000 UTC

Comments

Chip

Awesome, there is still so much for me to learn. =)

Darryl Godfrey

Hi Chip: thanks for your reply. Since my post, I figured out the answer myself with a hint or two from datasheets: the converter is running in Discontinous Conduction Mode which is governed by the load current plus the size of the inductor. In DCM a very different equation applies and producing a high voltage is fairly easy. The trick is to keep the current low so that the converter doesn't shift to CCM.

Chip

I just got done watching video #74 which is 2 videos before this one and I believe he explains how at 17 minutes and 48seconds in the video with the inductors and the fets in the circuit (by pulling the inductors down to ground, which I visualize as sort of charging them up and then releasing them which then lets them discharge releasing the stored energy as an increase in current and voltage). A little later he explains that by changing them he can change the output voltage and current. I hope this is the information you were looking for, I'm still pretty new to electronics so you'd probably know better than I would, but I hope this helps.

Darryl Godfrey

Hi Paul. It's unlikely that you'll see my question, but here goes: I've been puzzling over this circuit for months now. Not because I don't understand how it operates, but because all the references on boost converters give the formula of Vo = Vi/(1-D) where D is the duty cycle. I'm sure you've seen this. I'm currently reading a text book on switch mode power supplies (yeah: I don't have any friends!) and it says the same thing. Going further, it says that in practice Vo/Vi is limited to about 4 or 5 for various reasons. So what gives? I'd love to know how you managed a Vo/Vi of 17+ (200V//12V)!!!! Thanks for any insights into this - I've been pulling my hair out.