Unfortunately there is not standard marking on ferrite inductors.  My
main remaining concern is the inductance value.  Is this part of
switching regulator?  Or is it just an interference filter on the power
line leaving the regulator?  If it is just a filter the inductance is
probably not critical and an inductor of sufficient current rating and
similar physical size should be fine.  If it is an active part of a
switching supply the inductance is more important.  If one side of the
inductor connects directly to the switching IC or to a discreet
switching transistor it is probably an active part of the regulator.  If
the switching supply is a "black box" on its own then the active
inductor will be buried deep inside it and what you have is just a
filter.  If it is active the inductance could be measured with an
inductance meter if you have an intact inductor to measure.  Otherwise
look at the manufacturer's recommendation on the switching regulator IC
datasheet.

Sherpa Doug

> -----Original Message-----
> From: SM Ling [mailto:piclister@YAHOO.COM]
> Sent: Tuesday, December 18, 2001 10:26 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE] what's this smd inductor
>
>
> > Is it on a specific board one of us might know about?  Can
> you tell us
> > what the -12V regulator chip is?   If so look at the sepc
> sheet for the
> > chip.  Otherwise you will just have to build or borrow something to
> > electically measure it.
>
> Thanks Doug,
>
> -12V which come from a switching supply goes through the
> inductor to power
> some op. amplifiers and a 7905.  It is on a VME card,
> somekind of video
> board.
>
> After studying the catalgoue and pictures further, I think
> this is a SMD
> ferrite.  So I measured the current with a multimeter, it
> peak about 490mA.
> Combing through the MuRata list, I think I could choose
> either a 600mA or a
> 1000mA.  I am thinking to go for the 1000mA.  Isn't there a
> standard for
> these things if they could not put a marking on them ???
>
> I also have measured the W and H wrong, they should be 1.6mm.
>
> cheers, ling sm
>
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