Xinhua Rong wrote:
> Hi all,
> I am quite new to switching power supply design. I found in the recommended application diagram of MAX series there is one 100uH inductor. I wonder there is any requirement about this component. My current consideration is: big enough current,
> low loss (high efficiency),
As long as you use the largest wire that will wind the number of turns (single layer) to cover the core.
> high frequency (how high? several MHz?).
More like 1 mhz should be fine.
> If I have to homebrew it, what should I do? Such as, how many turns on Amidon FT-50-47 toroid? Thank you for your help!
Use 38 turns of 24 gauge wire and that should put you at about 100 uH. There is a formula for determining the number of turns for a given permeability core. Unfortunately, you need a data sheet from Amidon that specifies the AL (inductance in mH / 1000 turns of wire), from this AL value you can calculate the
turns to reach your inductance:
Number of turns = 1000 X ---------------------
/ desired inductance in mH
/ AL value (mh/1000 turns)
the formula is "1000 time the square root of (desired in mH divided by AL)"
I got my winding sheet from them many years ago when I purchased a couple of experimenters kits.
-- Tom Walsh - WN3L - Embedded Systems Consultant 'www.openhardware.net', 'www.cyberiansoftware.com' "Windows? No thanks, I have work to do..."
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