How to use 4 pins inductor

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lloydi12345

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Hi I have this inductor RCH110NP-151K. It is 150uH rated. Based on the schematic, I connected its pins 2 & 4 to my MC34063A DC-DC Converter IC. Then my IC smoked. I then realized that pins 2 & 4 are connected to each other. How can it be? On the schematic there's an inductor symbol. I tried using the other pair of pins left on another MC34063A but the IC doesn't seem to function.

Anyone used this inductor already?
 
The actual resistance between the pins will be very small. There are only a few turns of wire on the inductor. The inductor works by passing a current through it then turning off the current the inductor produces a voltage in the opposite direction. This voltage and the current it delivers is used by the output of your circuit.

You have to make sure the circuit is oscillating so that a very large current does not flow though the inductor and the other components. This high current will be delivered by the output of the IC.
The only way to protect the IC is to put a 22R 0.25w resistor in place of the inductor. Feel the temperature of the resistor after 5 seconds. If you have a CRO watch the output of the IC.
If not, get a 10mH choke with 33R resistance and put it across the 22R. Now measure your output. See if it is generating a higher or lower voltage as required. The voltage will not be exactly as required but the IC will not be damaged. Gradually work towards the value of inductance required.
You should have done some protection-work like this before frying the chip.
The other way to protect the chip is to put a 22R in series with the supply. Or alternatively use a 12v supply from old batteries.
I have never fried a chip.
 
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colin, I don't know WHERE you learned how an inductor works, but you are way off!

An inductor allows DC to pass freely through it with no opposition. It only opposes current flow when you have an AC signal/voltage. The inductor does not "pass a current through it then turn it off". I have no idea where you get your information. I could go through all the math about how an inductor really works, but I'd rather not, as it involves somewhat complicated calculus equations. Instead, I'm just going to say that it passes DC but opposes AC. That is in layman's terms, so hopefully it's easy to understand. Perhaps you should do a little bit of reading on the subject, colin

lloyd, are the pin numbers actually labeled on the case? Also, are you sure that is the datasheet for the inductor you have? And what about the circuit you're using it in--why do you need an inductor connected to a chip? A schematic would be much appreciated here

Best wishes,
Der Strom
 
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Perhaps you should try reading the thread instead of jumping in with both feet?.

He was obviously referring to the specific use of the inductor in this switch-mode circuit.
 
Colins wording is a bit ambiguous:
The inductors works by passing a current through it then turning off the current and the inductor produces a voltage in the opposite direction. This voltage and the current it delivers is used by the output of your circuit.
Click to expand...


If it is re worded as:

In this circuit the inductor works by passing a current through it, then when that current is turned off the inductor produces a voltage in the opposite direction.
This voltage and the current it delivers is used by the output of your circuit.

the meaning becomes a bit clearer.

JimB
 
I'm just going to say that it passes DC but blocks AC
Click to expand...
No wonder nobody has ever understood how an inductor has worked.
No wonder I get 320GB of traffic to my site each month.
 
To be quite honest colin...the ONLY place where D8 got it wrong was by stating that it "blocks" AC. He should've stated that they "oppose" AC.
 
You have a person who is blowing up an IC because he does not know:
1. How to protect the circuit from being damaged if a fault exists,
2. How the inductor works.

I let it go for a day and no-one replied to help him.

It is absolutely pointless to tell him an inductor opposes AC and only passes DC.
He needs to know in simple terms how the inductor works and how to prevent further damage to the circuit.

I never said: “an inductor passes a current through it then turns it off".

Of course I am assuming the OP is making a switch-mode arrangement and using the inductor for either boost or buck. It’s in these arrangements that the circuit impedance is very low and any fault will instantly destroy the chip.
 
colin55 said:
I never said: “an inductor passes a current through it then turns it off".
Click to expand...

As JimB said, your wording was very ambiguous and really is not the best wording (not to mention it is a very poorly constructed English sentence anyway).

The inductors works by passing a current through it then turning off the current
Click to expand...
 
It's days like this that make me wonder if anyone that visits this forum is sane!

Colin, where did you get your information for the suggestions on the alteration of the circuit? Considering that the original poster didn't post a schematic or circuit diagram of any kind, the only reference was to the datasheet of the inductor.

Anyone that's made any comment on what might be wrong must be psychic!
There are a dozen or more things that have nothing whatsoever to do with the inductor itself that could be wrong with the circuit, and without that circuit that the poster made this post was dead on arrival, it's no wonder anyone responded to it at all, no one should have!
 

That is exactly why I suggested posting the schematic in my first post. I'm pretty sure I said all this already, just in a slightly more polite way....
 
Derstrom, you posted it 2 paragraphs after ripping into Colin.

There is figuratively, logically, and rationally no conversation that could have progressed that has occurred that could help the original poster that hasn't already occurred which requires anything more than them to provide more information.

This thread was dead on arrival from the first post. I'm highly curious as to Nigels reason for interjection as there isn't a circuit to analyze from the start.. Nothing but assumptions.
 
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Sceadwian said:
Derstrom, you posted it 2 paragraphs after ripping into Colin.
Click to expand...

What does it matter where I said it? The point was that I asked for the schematic before trying to help. I'm still waiting for a reply from the OP before I even consider the actual question. The thread was not dead on arrival. It is simply one of those that just needs a little more information before it can really come alive.
 

Sorry DerStrom, but you were two paragraphs beating on Colin before you tried to help, and the last sentence of a post that large was NOT relevent to the original post. Neither was Colin's post in my opinion.

I would love nothing more than to see the original poster to comment on this thread and repost.
 

Two paragraphs? Are you counting a single sentence as an entire paragraph? Think of it more as a lead-in to what I was saying to colin.

Again, I ask what does the placement of my questions to the OP have to do with anything? I asked questions regarding his first post, and requested a schematic. I don't see why you're having an issue with this. I tried making a simple correction/explanation, and then led it back into what the thread was originally about. I know I posted something aimed for colin that wasn't answering the OP's question, but what do you think you're doing now? You're arguing with ME about something that has no more to do with the actual thread than what I posted! If you're not willing to help, and you're just here to argue, please just lay off. This thread is for helping with a question about how to use a certain inductor, not about arguing with something the other members said.
 
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There is no possible correction to be made on a circuit or meaning that can be made on a post which has no circuit or schematic to base any conversation from to begin with..
 
Sceadwian said:
There is no possible correction to be made on a circuit or meaning that can be made on a post which has no circuit or schematic to base any conversation from to begin with..
Click to expand...

The correction was not about the OP's question. It was about a poorly-written post by colin55. The only response to the actual question was my request for a schematic.
 
Hi I'm really sorry I missed to place the schematic. It's because I'm assuming you'll be using the circuit of MC34603's default template.

Okay here's the setup. 220VAC>>Transformer>>24VAC fed through the rectifier diodes with 1000uF 50V caps on it. After that, the voltage output around 32V is fed directly to the circuit of MC34603 which I found from the site https://www.bobtech.ro/tutoriale/co...e-mc34063a-mc34063-step-down-step-up-inverter

Here are the values I placed for the calculator:
Vin 32V
Vout 9V
Iout 750mA
Vripple 18mV
Fmin 25Khz

And here are the values that came out:
Ct=479 pF
Ipk=1500 mA
Rsc=0.2 Ohm
Lmin=176 uH
Co=417 uF
R1=1k R2=6.2k (9V)

I assembled them exactly as I could on a breadboard. I used 470pF non polarized cap instead of 479pF, 470uF elec cap instead of 417uF. I used also 0.2ohm 2W resistor. R1 and R2 are also with the exact values. I didn't missed using 1N5819 on the circuit. The only different thing and I doubt the most is the inductor which I said I used RCH110NP-151K. It is rated 150uH.

That is the exact part number the seller gave me when she handed me the inductor.

I just don't think I'm good on how to use this inductor. It would be easy if it's just 2 pins because I'll just plug it on the board but it has 4 pins so I'm having a hard time dealing with it and the datasheet seems not to be so specific or lacking some examples. I'm currently looking for more examples to understand how to use this.

Thank you so much for those much much inputs I got from you. I will be waiting for more details.

Regards,

lloyd
 
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Hi lloyd. Thanks for replying

First I must ask, have you used the exact same components as shown (or calculated) in the schematic, and connected them the exact same way, or have you made any substitutions for parts you don't have? If there's anything at all that you have changed from the original values, it would help for you to let us know. Sometimes the slightest change of a single component can make a huge difference.

Regards
 
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