Electronics > Projects, Designs, and Technical Stuff
Do I need shielded chokes for noise suppression
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Simon:
I am working on a project where we have common mode noise and differential mode noise. So i will use common mode inductors and single inductors. Do these inductors need to be shielded considering we have to undergo radiated noise tests? the system is inside a metal box so i suspect most of it is being conducted out rather than any radiated stuff getting out.
nctnico:
No. But just make sure the noise isn't coupled into the wires through the ground plane.
T3sl4co1l:
Doing what, and how?

EMC is a holistic study.  It is impossible to say anything without full details of the system in question.

Also, mind that ferrite beads saturate at fairly low currents, so you may not get the impedance you were expecting, using one on a power line.  Better to use a CMC, or a real inductor.

Tim
coppercone2:
well if your gonna slap some parts in it I figure your gonna get better performance from a shielded choke the only thing it will have is like slightly higher parasitic coupling to ground/shield but its probably going to be almost nothing. I think you could take it into account if your doing a cable drive budget with how many pF it can drive but I am not sure actually, since its energy loss from the charge pump usually.

The good precise old HP instruments I have all use shielded chokes.
Simon:

--- Quote from: T3sl4co1l on November 19, 2018, 02:21:10 am ---Doing what, and how?

EMC is a holistic study.  It is impossible to say anything without full details of the system in question.

Also, mind that ferrite beads saturate at fairly low currents, so you may not get the impedance you were expecting, using one on a power line.  Better to use a CMC, or a real inductor.

Tim

--- End quote ---

I am looking at this one: http://katalog.we-online.com/pbs/datasheet/7448680140.pdf I have a problem in the 80-100MHz range. Because my boss is an idiot he thinks he can batch test multiple projects for EMC which means I just get a result back of a failure on the standard test and have no idea where the noise is actually coming from.

I was thinking of using that part as a differential choke as well putting the coils in parallel or would series be better?
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