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Being a newbie hobbyist, I have a hard time finding a certain part or a replacement.

I plan to control a few electroluminescence wires via a microcontroller. The tricky part about these is that they need to be driven by a "higher" voltage (about 60 V to 120 V AC) and frequency (somewhere between 400 Hz and 2 kHz, it seems).

There are several possibilities here but to me the most appealing one is a nice IC with an I²C interface that can drive up to four wires/panels: Maxim MAX14521E.

Getting that isn't the problem, but it requires a tapped inductor for operation. The datasheet mentions the following values: 2.3 μH/115 μH, 1:7 ratio (ISAT = 0.7 A, RS = 1 Ω). I wasn't able to find such a component (or any "tapped inductor" for that matter) in the typical electronic component shops, which undoubtedly is due to me not knowing under what kind of "aliases" such a component may be known, or how to search for it. As far as I've understood, it's a single coil inductor with an additional contact "in between" both ends but I'm not even sure about that.

There's a part specifically made for the MAX14521E which is often used (it's used in Maxim's development kit and also on other boards that I've seen using this chip): the Coilcraft GA3250. It's characteristics are 1.9 μH/112 μH, 1:8 ratio (ISAT = 0.7 A, RS = ?). Unfortunately, it's only available via the manufacturer's homepage with ridiculous shipping fees and takes a whopping 9 weeks delivery.

So I need to find a different part that does the job but I have no idea how to actually search for one. What are the common names for these parts and how do I find them in the large electronic component online shops?

I lack the vocabulary and knowledge to actually do a search for similar components and would like to know which terms and parameters (for the parameterised searches) are going to help me find a replacement.

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    \$\begingroup\$ Wind it yourself if you don't need that many? \$\endgroup\$
    – winny
    Jan 10, 2017 at 15:24
  • \$\begingroup\$ Never wound a coil myself and there's already enough challenging parts for me to master to make my project to work. But thanks for the suggestion. \$\endgroup\$
    – DarkDust
    Jan 10, 2017 at 15:45
  • \$\begingroup\$ It's a great learning experience to differentiate yourself from the Arduino PWM-mob :-) \$\endgroup\$
    – winny
    Jan 10, 2017 at 15:58

2 Answers 2

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The datasheet mentions the following values: 2.3μH/115μH, 1:7 ratio (ISAT = 0.7A, RS = 1Ω).

The data sheet also contains this: -

enter image description here

So, if you are looking for aliases I would recommend you look-up these parts to understand the names they use.

Basically, it isn't a tapped inductor, it's a coupled inductor or transformer with a couple of the pins joined together when you wire it up. See this for instance: -

enter image description here

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  • \$\begingroup\$ What do you mean with "look-up these parts to understand the names they use"? Look them up in the shops? Mouser doesn't have either and DigiKey doesn't have the Coilcraft part (can't check for the Cooper, DigiKey's search is broken right now). But according to your last paragraph, I can just use two fixed inductors (one with about 2µH and the second with about 115µH) instead? \$\endgroup\$
    – DarkDust
    Jan 10, 2017 at 15:42
  • \$\begingroup\$ Google them. I did. Well I googled the coilcraft part hence the picture in my answer and hence the names they use. My last paragraph certainly does not imply you can use two fixed inductors - how would they couple magnetically. \$\endgroup\$
    – Andy aka
    Jan 10, 2017 at 15:58
  • \$\begingroup\$ I already linked the Coilcraft datasheet in my question, I did google it… that's not the problem. My problem is: how do I find a part like this in online shops like Mouser, DigiKey and so on? \$\endgroup\$
    – DarkDust
    Jan 10, 2017 at 16:04
  • \$\begingroup\$ @DarkDust if you cant search D-K, choose the basic category 1st then search \$\endgroup\$ Jan 10, 2017 at 16:56
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    \$\begingroup\$ Okay, we're really getting further and further away from my question. Thank you all for feedback, really, but my core question has not been answered so far and I fear that I will not get it answered. Maybe I should rephrase it completely: What are synonyms or terms with which I can find what Maxim calls a "Tapped Inductor" in its MAX18210E datasheet? Two such components (GA3250 and CTX03-18210) are mentioned in the datasheet but since I can't get them I need something similar from a different company that I can order. I do not want to wind my own, that just adds another headache. \$\endgroup\$
    – DarkDust
    Jan 10, 2017 at 19:10
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The datasheet schematic alone tells clearly that the coils should have a common core. The text uses transformer terms primary and secondary and tells the winding ratio should be 1:7 which implies inductance ratio 1:49. As others have said a transformer with proper ferrite core (for the frequency and allowed magnetization) can be used, only connect one end of the primary and one end of the secondary together so that the winding continue to the same direction at the connection point (as shown with the black dots in the schematic).

I'm afraid that to get one with specified primary and secondary inductances and allowed resistances and currents with no saturation you must either make the right one by yourself or order a custom model.

You seemingly eagerly wait hints for a substitute. But there cannot exist a substitute without redesigning the integrated circuit. So: Make the specified transformer by yourself. That's quite a common way also for the rest of us who want to build a circuit which is designed to have a certain inductor or transformer. Only the very best of us are sometimes able to redesign a whole already designed and well working circuit so that the wanted function is got with inductors they happen have or can easily buy.

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