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ADP2303 inductor question

Question asked by SebTC on Jul 4, 2014
Latest reply on Sep 3, 2014 by power-layout-guy

Hello,

 

Recently I made a buck converter with the ADP2303 5V fixed output using the circuit given in the ADP2303 datasheet. Input 12V, output 5V. Components are as recommended by the datasheet, except for the inductor. I needed a 4,7uH inductor and thought the Bourns PM127SH-4R7N-RC (http://www.bourns.com/data/global/pdfs/PM127SH_series.pdf) would be good. Made 2 identical circuits with this inductor, didn't work. THe voltage was 5V until I added a load, even a small load lowered the voltage to 2V.

 

Removed the inductor and soldered a self made coreless inductor (cable wounded 30 times measuring around 4,7uH), this worked fine for all loads. Why didn't the Bourns inductor work, is it like a choke inductor? Couldn't find that word. Hope somebody can help me with this, so I'm not going to make the same mistake choosing a new inductor.

 

Thank you for your help.

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