Although the thread is rather old, I want to give some comments:
To the inductor: In the pictures I could see, it had 18µH, at least before some part of the ferrit was broken off. Now it sure has less.
To the chip: Here is the datasheet: ...here was a link to the datasheet... but the forum software does not allow me to post links, so you have to search yourself: type the name of the Chip (PR4401) into google, use the first link like: www . prema . com / pdf / pr4401 . pdf
It says, the peak current is up to 250mA. But it describes, how to use a capacitor (0805 size is enough) and a schottky diode to smooth it out, like in a normal step up converter. An additional cap in parallel to the battery is also a good idea.
Otherwise very nice!
To the inductor: In the pictures I could see, it had 18µH, at least before some part of the ferrit was broken off. Now it sure has less.
To the chip: Here is the datasheet: ...here was a link to the datasheet... but the forum software does not allow me to post links, so you have to search yourself: type the name of the Chip (PR4401) into google, use the first link like: www . prema . com / pdf / pr4401 . pdf
It says, the peak current is up to 250mA. But it describes, how to use a capacitor (0805 size is enough) and a schottky diode to smooth it out, like in a normal step up converter. An additional cap in parallel to the battery is also a good idea.
Otherwise very nice!
