Re: SEPIC Converter oscillation

MooseFET wrote:

On May 3, 2:09 am, QQ <q_q_...@xxxxxxxxxxx> wrote:

Hi,

I am trying to simulate a SEPIC converter in HSPICE. I find that there
is an oscillation at the switch node (drain of the mosfet) as well as
the second node (other end of the flying capacitor) but the output is
stable and at the correct value. The sinusoidal noise rides on the
switching waveform. Any idea what is the cause of this noise?

I suspect the noise may be because of some kind of resonance between
the inductors and capacitors but I am not sure what exactly or how to
eliminate it. Any help in understanding this is much appreciated.


I assume this is a high frequency thing on the drain of the MOSFET.
It is likely the capacitance of the MOSFET and the inductor
interacting.

Is it really a problem? It may just be the normal sort of ugly wave
form you see in switchers. If this is the case, don't try to get rid
of it. Anything you do to get rid of it makes a new and real problem.


If it's not a ringout with a fast decay but a stable oscillation this might fly into the OP's face at the EMC lab. When they give the thumbs down for EMC cert.

--
Regards, Joerg

http://www.analogconsultants.com
.

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