Rc over diode

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Hey

Jeg har lavet mit en switchmode supply..

er der nogle der kan fortælle lidt om det rc man normalt sætter over
ensretter dioderne... mest af alt hvordan man regner det ud :)

Mvh

Kasper



Re: Rc over diode

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Hej Kasper

Kig på denne adresses smps adresser:

http://da.wikipedia.org/wiki/Smps#Design

F.eks.

Snubber Design Tips:
http://www.ridleyengineering.com/snubber.htm
Citat: "...
If you have any ringing waveforms in your power circuit, these waveforms
must be damped or they can lead to device failure, excessive EMI, or
instability. In many cases, you can damp a ringing waveform with a
series RC network across the offending device
...
Try an initial value of snubber resistor of R = Z. This usually suffices
to control the ringing.
..."


http://www.smpstech.com/weblog/index.htm#DIODELOSS
Citat: "...
Answer: Since the boost diode conducts in the reverse direction until it
recovers, the turn-on of the power MOSFET is controlled by the diode
characteristics, not the power MOSFET or its drive. In fact, best
performance is usually had by matching the turn-on of the MOSFET to the
diode by slowing down the MOSFET
..."

-

Kig især på SiC dioder - de overflødiggør stort set RC-dæmpeleddet(eng.
snubber network) over diode(rne) pga. af ultra fast
recoverytid(<50nSek)/zero reverse recovery charge - kig f.eks. på figur 3:

http://da.wikipedia.org/wiki/Smps#Design_-_effektivitet

Cree: SiC (Silicium Carbon/Carbid) Power Schottky (Barrier) Diodes (SBD)
in Power Factor Correction Circuits (pdf):
http://www.cree.com/ftp/pub/CPWR-AN01.pdf

mvh/Glenn

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Re: Rc over diode [SiC masseproducerede dioder]

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Hej Kasper

Fra:
http://da.wikipedia.org/wiki/Halvleder

Er adressen på et eks. på et firma som masseproducerer SiC dioder fundet
- med datablade:

thinQ!™ 600V SiC Diodes.
600V Silicon Carbide Ultrafast Schottky Diode:
http://www.infineon.com/sic
eller
http://www.infineon.com/cgi/ecrm.dll/ecrm/scripts/prod_ov.jsp?oid22%164
Citat: "...
Features:
     * Revolutionary semiconductor material - Silicon Carbide
     * Switching behavior benchmark
     * No reverse recovery
     * No temperature influence on the switching behavior
..."

Infineon Technologies Produces Worlds first Power Semiconductors in
Silicon Carbide:
http://www.chipcenter.com/power/powp364.html (adresseindhold ændret -
desværre)
Citat: "...Due to its unique characteristics, the silicon carbide (SiC)
material has high blocking voltage capability (up to 3500V) resulting in
a higher schottky barrier, ten times higher electrical breakdown field
strength, and a thermal conductivity comparable with that of copper. ..."

mvh/Glenn

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