RE: [SI-LIST] : Bulk Caps -> Inductor? -> Plane

About this list Date view Thread view Subject view Author view

From: Tom Dagostino ([email protected])
Date: Tue Apr 11 2000 - 14:13:36 PDT

We used to do this kind of thing all the time in oscilloscope designs. The
purpose is to keep noise generated on the board from poluting the power
distribution system. The LC network acts as a low pass filter. There
should be C on both sides of the L. You will not really draw the current
spikes through the inductor, there will be some average current passing
through it charging the C on the board side of the L. The distributed C on
the board will be charged from that bulk C, thus the sizing of that bulk C
is important.

Tom Dagostino
ICX Modeling Group
[email protected]

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of mjs
Sent: Tuesday, April 11, 2000 11:59 AM
To: [email protected]
Subject: [SI-LIST] : Bulk Caps -> Inductor? -> Plane

I am not sure if the list accepts attachments, but here goes.
If the attachment is stripped by the listserve, please find
it visible at (16k)


The attached gif show a snip from a schematic currently in layout.

The transformer shows the secondary of the SMPS, connected to a whole mess of bulk capacitance, especially on +5V net.

Please note L202 series inductor inserted between the bulk capacitance and the connection to the power plane. This worries me most. There seems to be no valid reason to stuff series inductance between the bulk and the plane. Further, all the local ceramic IC pin bypass will also have to suck current through that same inductor. Seems like a terrible idea to me. Comments welcome.

Matt Stanik Sr. PCB Design Eng. Charles Industries, Ltd.

**** To unsubscribe from si-list or si-list-digest: send e-mail to [email protected] In the BODY of message put: UNSUBSCRIBE si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP. si-list archives are accessible at ****

About this list Date view Thread view Subject view Author view

This archive was generated by hypermail 2b29 : Thu Apr 20 2000 - 11:36:08 PDT