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Old 3rd December 2009, 05:22 PM   #1
ICE_Mag is offline ICE_Mag  United States
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Default Inductor Evaluation Help

I am looking for help evaluating a new line of inductors my company is developing specifically for Class D inductors. We have completed the design and evaluation from a magnetics point of view and have had a couple of our parts qualified on the IRAUDAMP7D and the IRAUDAMP7S reference design from IR. Unfortunately, neither I nor any of our engineers feel qualified to evaluate their performance by listening to the sound quality.

I'm interested in offering free samples in exchange for feedback on audio performance. Of course, if anyone can provide quantitative test results to back up their subjective evaluation it would be more the we can ask for but appreciated greatly. We have three series available, each with 10, 15, 22 and 30uH values. If you are interested, let me know and I can send our preliminary data sheets to you.
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Old 4th December 2009, 06:08 PM   #2
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Can you tell us anything about the type of inductors they are and what sets them apart from other products on the market?

Core type?
Core material?
Gapped?
Litz wire?
Alien technology?
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Old 4th December 2009, 06:59 PM   #3
ICE_Mag is offline ICE_Mag  United States
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I've tried to attach the catalog pages. These use gapped ferrite in a new core shape made for Class D applications. The advantages of the cores shape are shielding and a small winding area vs cross section since the inductance values are not large. The ferrite is made by a Japanese manufacturer and has a relatively stable permeability over temperature.
Attached Files
File Type: pdf 1D10A.pdf (114.5 KB, 151 views)
File Type: pdf 1D14A.pdf (116.3 KB, 63 views)
File Type: pdf 1D17A.pdf (116.2 KB, 107 views)
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Old 4th December 2009, 07:35 PM   #4
fredos is offline fredos  Canada
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Send me fews 1D17A-330M, for sure I will evaluate them! support@d-amp.com
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Old 7th December 2009, 08:30 AM   #5
audi0 is offline audi0  Australia
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Default Inductor evaluation

Hi ICE_Mag,
I would certainly be interested, I have spent a whole lot of time researching inductors and comparing air-core to toroids, if you are willing, the 10uH are the ones for me! TA-2020 chip.
I would be delighted to help out

cheers.. Steve
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Old 7th December 2009, 02:43 PM   #6
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Do you also intend to specify parallel capacitance ?

Regards

Charles
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Old 8th December 2009, 09:07 PM   #7
ICE_Mag is offline ICE_Mag  United States
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We don't use the term parallel capacitance in our part of the magnetics world. Do you mean turn per turn capacitance or the total capacitance between turns? If yes, why do you need it? Will it help you to calculate SRF?
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Old 9th December 2009, 10:58 AM   #8
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Parallel capacitance of output inductors (i.e. total capacitance per finished coil) and series inductance of the cap parallel to the load make the output filter behave less like a lowpass filter with raising frequency. Unfortunately it is the higher frequencies that are responsible for a class-d amplifiers external (i.e. speaker wires etc) EMI radiation.
If you make this capacitance as low as possible by the use of a clever design (like avoiding multiple layers of windings for instance) you help the class-d designer designing for low EMI.

Regards

Charles
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Old 10th December 2009, 07:54 PM   #9
ICE_Mag is offline ICE_Mag  United States
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I did a little checking and our parts use both one and turn layers depending on the size of the core and the inductance value. Thanks for the insight.
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Old 11th December 2009, 06:37 AM   #10
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If you have anything above 40A and I-sat more than 60A, i would surely like to evaluate the performance.
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