Saturation of ferrite core in SMPS?
Saturation of ferrite core in SMPS?
(OP)
Hi,
I am designing an offline, isolated flyback at 22W with Vout = 36V, Vin=85-265VAC.
I will be using a EFD25/13/9 ferrite core transformer from Epcos(the AL = 315 one, N87)
Ferrit core datasheet:-
http: //www.epco s.com/web/ generator/ Web/Sectio ns/Product Search/Hit list/Ferri tes/Ferrit esAndAcces sories/EFD EVDECores/ Page,local e=en.html? param_head line1_en=E FD+25%2F13 %2F9&p aram_headl ine2_en=&a mp;param_m aterial=&a mp;param_a l_value=&a mp;param_a l_value_to l=&par am_air_gap =¶ m_terminal s=&fro m=searchfo rm&doA ction=sear chform& ;view=& ;distribut orId=0& ;cssurl=&a mp;shop=no
On page 2 of the datasheet, it says Pv W/Set is 200mT....
http://i54.tinypic.com/34owms7.jpg
....but i thought the saturation flux density of most ferrites was 300mT?
My peak flux density is 220mT.
-do you think this will saturate this core?
I am designing an offline, isolated flyback at 22W with Vout = 36V, Vin=85-265VAC.
I will be using a EFD25/13/9 ferrite core transformer from Epcos(the AL = 315 one, N87)
Ferrit core datasheet:-
http:
On page 2 of the datasheet, it says Pv W/Set is 200mT....
http://i54.tinypic.com/34owms7.jpg
....but i thought the saturation flux density of most ferrites was 300mT?
My peak flux density is 220mT.
-do you think this will saturate this core?





RE: Saturation of ferrite core in SMPS?
EPCOS used to be Siemens components division, hence the French
You are safe with 220 mT. No problems.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Saturation of ferrite core in SMPS?
RE: Saturation of ferrite core in SMPS?
hgldr:
did you calculate the 3We from the N87 material datasheet?
i thought EFD25 was about right for 22W SMPS at 100KHz?
also, i presume you are referring to core hysteresis loss's?
RE: Saturation of ferrite core in SMPS?
Sorry, I was thinking of +/- 2.2kG and for a different core material. I think you're fine. Your 2.2KG peak flux roughly correlates to a +/-1.1kg flux swing with a sine wave. Since it's 1.8W max at 2kG (in the spec which I just looked at) your loss will be much less.
P = 1.8W times the ratio of: (1.1kG/2kG)^Kb Where Kb is usually 2.4 to 3.0 for most materials, so it looks like you're at no more than about 0.43W.
To answer your basic question, the core can handle about 3kg (or 300mt). the 200mT in the spec is a data point for the loss at 200mT. They don't mean that it's peak flux is 200mt.