Inductor DC current rateing peak current

Inductance versus frequency is to some extent documented by the self- resonance frequency of the inductor, which is usually given. You can convert it to a parallel capacitance.

The Bourns parts are wound with a single layer of widely separated turns of wire, for which the parallel capacitance usually comes out as of the order of 1pF, which would put the lowest self-resonant frequency around 5MHz and the highest closer to 50MHz

It could be that the losses due to induced currents in the core would kill any such resonance, but pre-wound inductors are pretty much always designed such that the self-resonance is tolerably sharp, so that the inter-winding capacitance sets your upper frequency limit.

Commercial pre-wound indusctors are generally designed so that they don't saturate below the DC current rating at the maximum rated working temperature - which is usually set by the Curie temperature of the core material.

-- Bill Sloman, Nijmegen

Bill Sloman wrote

SRF is not given in the 1 page data sheet.

I would hope it wouldnt satuarate below the DC limit or else the spec would be useless.From what I recall any rateing DC or RMS current is set by copper losses peak current is set by core material and size.A massed produced inductor isnt going to use oversized cooper if the core cant handle the energy.

They show a 43% drop in inductance at rated current. The core material is'nt stated but I'm guessing it is'nt ferrite.

If they have a color photo, you can guess the material type.

Mix 26 and 52 are quite popular, and fairly lossy (e.g., a typical DCM = boost supply will have very little "dead time" ringing using these, = whereas a ferrite core, with much lower losses, will ring = significantly).

Tim

--=20 Deep Friar: a very philosophical monk. Website:

supply will have very little "dead time" ringing using these, whereas a ferrite core, with much lower losses, will ring significantly).

Well yes I guess I could , but should you really have too? They are trying to sell a product so they should be providing the information without someone having to jump through a bunch of hoops.

You would figure they would have more detailed specs on their site but after browsing through the site and their catalogues they don't.

If I wanted to build 5k a year what do you have to do email some clown in sales and ask for specifications that should already be included in the data sheet.

I'm not just talking about the one inductor I posted about but the majority of inductor data sheets,if they can even be called that only state a dc current rating and maybe Q and srf.

I'm just going to use the coilcraft part at least I know what I can expect.

Its for a NCP1654 "CCM" boost converter.

Must be a barrel choke.

-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

Whats the lead time on that 1654? Mouser shows 4/18/2011

Coilcraft is good, easy samples. There are others

Check CWS

they might have something competitive .

I used the IRF1150, same CCM topology, the loop works well when setup properly. But bypass Vcc well, and pick a mosfet with low input capacitance.

Cheers

Onsemi shows call under lead time.

But between Digikey and Newark alone they have over 3k in stock.

Newark

Digikey

Yes the inductors I have are from the NCP1653 300W PFC demoboard.I think Onsemis phaseing out the 1653 for 1654.

I agree Coilcraft is excellent for samples as well as no hassle small quantity orders.

The 1654 has a pretty beffy drive output +/- 1.5A.

So did the 1150, but we had to buffer it to drive the IGBT we used ;)

Onsemi give me tingles on lead time for smt parts, I might as well use the thruhole parts. P&S is suppose to have small qty stock, never tried them yet.

I have a few NCP1601's that I am going to experiment with in a SEPIC design. I'm hoping to run close to 200khz with it. Trying to shrink the previous design.

Cheers

Was the controller over heating or did you use the buffer to speed transitions?

I cant even find a data sheet on the 1150 not even at IR or Vishay it must be discontinued. I vaguely recall reading something a while ago about single cycle control. I guess it didn't catch on ;-)

I'm building this mainly for experimentation the input range is only

90 - 135VAC. So the output is going to be 200VDC. So I can cheat and use a fast switching low gate charge FET LIKE THE std17nf25 and cheaper 250V output caps..

Never heard of P&S either but going to the site is all in Chinese so I probably don't want to know about them ;-)

I'm sure if you wanted more then the 3300 digikey and Newark stock On semi would work something out.

The bom for the 1654 is pretty minimal pg 22 of the data sheet shows a

300W converter. If you go to high in frequency any gains in downsizing the BOOST inductor would probably be lost in having to increase the common mode choke for EMC.

The flavor of the month which according to availability from digikey is the FAN6961SZ Which is a DCM controller.I haven't researched PFC boost controllers for a while but I thought CCM was the best mode of operation.

Heres the 1150

Similar to the ncp part. It could do 200khz.

TI also has the UCC28019.

Aside from the loop component values, and brown out, it's just about a pin-for-pin replacement.

We have a larger >1Kw design that used the 1150 and a large IGBT, the switching losses were a problem and needed a beefy driver.

Right now my design is at 100khz and filtering isn't an issue. Going higher may make that choke a tad smaller or the same size if nothing is availble as a replacement.

CCM is suppose to be a tad less in switching noise than DCM.

Good luck

Cheers

But, you need dI/dt snub or else your rectifier makes it all back (or = your switch gets toasty).

Not a problem is you use SiC rectifiers, but those are still a while off = in price :)

BCM is the best I suppose, certainly easier to snub and doesn't have the = ringing of DCM. Has spread-spectrum characteristics, which may be = handy.

Tim

--=20 Deep Friar: a very philosophical monk. Website:

switch gets toasty).

price :)

This paper all be it's 6 years old shows comparision of rectifier technologies in CCM boost and its really not worth paying for a SIC device until you start getting over 1kW output power.

I have a couple of soft recovery "Stealth diodes" I'll try. They tend to have a higher Vf. But if you dont have to use a snubber they might have better overall efficency.

ringing of DCM. Has spread-spectrum characteristics, which may be handy.

I think CCM is the best mode above 2 to 300W. DCM the peak and rms currents would start to get excessive.

Heres an IGBT for you Tim. Look at Vce sat vs temp. It shows Vce sat at 0.95 x the 25C value. The worst case Vce sat @ 25C is 1.7V.

I was using IRF1150 no wonder I couldn't find it.

I don't know what your output voltage is but if you could use a 500V FET this would give you half the conduction losses of a typical 1.7Vce sat IGBT For a 1kW design.I'm guessing between the IGBT and the bridge rectifier heat sink size is probably eating up the most real estate.

They aren't giving it away though.$27.97 Canadian $$.

pdf

Like I said to Joerg, why don't they make 1A SiC's? They'd be cheaper = than the big suckers, certainly not as cheap as a UF4007, but if you = have to rectify a Tesla coil, what else are you going to do?

That's true for the input side, but not much for the output.

You do see more advantage for polyphase converters, however. In = principle, you don't even need a filter cap if your 2 phase CCM runs at =

50% or higher duty cycle (or 3 phase at >33%). Though stabilizing the = voltage would be tricky to say the least. :)

BTW, do you know any good 2 or 3 phase converter chips (any CM) offhand?

Not bad. Impressively low Vce(sat). Mouser has them in stock, and the = price is similar to other Fairchild products.

Why the hell do they rate it for 100 ohm gate resistors? Is there some = dark side to them in peak dI/dt or dV/dt that I should know about? It = sure makes their switching time and switching loss figures look like = crap, which is very strange.

I've been looking at the FGA30N120FTDTU, too. 2V sat is pretty good for =

1200V. On the other hand, Fairchild's figures, like switching energy = and power dissipation, leave me wondering if I'm being International = Rectifiered again.

Tim

--=20 Deep Friar: a very philosophical monk. Website:

big suckers, certainly not as cheap as a UF4007, but if you have to rectify a Tesla coil, what else are you going to do?

don't even need a filter cap if your 2 phase CCM runs at 50% or higher duty cycle (or 3 phase at >33%). Though stabilizing the voltage would be tricky to say the least. :)

I've been looking for those too. I've been able to find a couple from National. I'm picking this one up next order its for a 170W interleaved flyback that's my next project after I finish this PFC. Its here.

They also have a dedicated two switch forward controller.

The pickings is pretty slim though.

They also have an application note on a bridgeless APFC at On semi. You started getting up around a kW power out dissipation in the bridge gets over 20W.

A 800 W Bridgeless PFC Stage

is similar to other Fairchild products.

side to them in peak dI/dt or dV/dt that I should know about? It sure makes their switching time and switching loss figures look like crap, which is very strange.

On the other hand, Fairchild's figures, like switching energy and power dissipation, leave me wondering if I'm being International Rectifiered again.

Yea the ratings are getting pretty much to be a joke.

Shooting from the hip?

Huh? I've never seen one less than an amp. Cree makes really fat SiC diodes such as this one but you've got to have deep pockets:

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

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There is but you have to politely ask. Sometimes they'll have to measure it and they only do that if you dangle a BIG carrot in the form of a fat potential purchase order.

Usually they state several values. For excample current for 30C or 40C temp rise, then current for 20% inductance loss and 30% loss. That's usually enough to design with. I wouldn't want to push an inductor much past -30% in the peaks although some folks go to -50%. Probably the same guys who won't shift before 6000rpm :-)

44% drop at I-rated? Yikes! Personally I wouldn't like to push that one to 4.9A peaks.

Mucho mejor :-)

You should see some oriental IC datasheets ...

--
Regards, Joerg

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Almost every Inductor datasheet I have looked at is 1 maybe two pages one page consist of packaging information. The other page just states DC current rateing DCR and maybe SRF.

Usually its for the whole series.What are they trying to save money on paper?

Yep thats what I figured. I'm useing the coilcraft part. I started the layout I'm just waiting for the parts to come for the supply its provideing the bus voltage for.

If they could only all be like that.

Dont get me started.;-)