Hi, sir/madame:
I am looking for 200V 10uH fixed inductor to build a 12V-to-200V buck converter using LT3757. A 10uH inductor sits in the path between 12V input and 200V output, so I need an inductor which tolerate 200V.
There is no search option of voltage rating for fixed inductor on the Digikey website. Is there any way to find them?
Thanks!
Brad Lin
@Brad_Lin, welcome to Digi-Key TechForum.
Would you help to share your circuit design about your voltage conversion?
Refer to datasheet, below is 8V to 16V input to 24V output boost converter circuit. It uses 10uH inductor.
However, it suggests using high voltage flyback topology for your application (12V input to 200V output).
Please see the snapshot below. Could you recommend a inductor for this circuit?
I will also ask ADI and see if I need to switch to the 2nd circuit you posted above. Thanks!
In your circuit, Brad, the 200V will be dropped across the Schottky diode, D26, not the inductor. Inductors are never rated in DC voltage anyway, because they are very low Ω. Yours is specified to be 30mΩ max (0.03Ω - basically a short circuit to DC)
Pin 2 of your Schottky diode will have 200VDC there. The junction of PL14, Q14, and D26 will be 12VDC (but your meter probably won’t like the high frequency, high voltage spikes there so I wouldn’t try to measure it with my meter)
Greg B
Thanks, Greg. Now I realize that why fixed inductors are not rated in DC voltage.
This is a boost circuit; I am not familiar with boost circuits. In this case, does the forward voltage of D26 matter?
Forward voltage is pretty low with Schottkeys. At 200V output, the forward voltage drop will be pretty irrelevant.
Sorry for the slow reply. I’m not on the forums every day.
Greg
