Identification: MOSFET IRF520 type

[optogeneticist]

Let me preface this by saying I am not an electrical engineer of any sort. I'm working on a small-scale automation project (Arduino) with a local college. I'm supposed to be doing software, but the responsibility of electronics has kind of fallen to me as well, because my peers consist mostly of intimidated biologists.

I can't find this exact MOSFET part on Google, but we need another one. What I want to know is either 1) where can I find this part or 2) where can I find a part that can do the same thing? I know the voltage/resistance can vary even amongst IRF520s, so that's why I'm asking.

(http://imgur.com/hcslXg8)

Sorry for ugly fingers, I had to bend the connector back a bit (yikes). I'm pretty sure the text says:

IRF520
I[symbol]R P540D
B9PO

Thanks for helping a novice like me, means a lot.

 

[(*steve*)]

The IRF520 is a relatively old school MOSFET.

It's rated for a maximum voltage of 100V, a maximum current of 10A, and has a channel resistance up to about 0.25Ω. As an old school device it also has a relatively low gate charge.

My question for you is "what are these used for?"

There are many possible replacements, but knowing what you're switching, voltages and currents for the load, and what is driving the MOSFET will all be helpful.

If you have a circuit diagram that would also be very useful.

 

[Bluejets]

If you are using with Arduino then logic level would be necessary.

 

[optogeneticist]

On my end, the project I'm on consists of maintaining an Arduino machine that will feed fish, and will flash an LED when food is ready.

Looking at the code from the Arduino, it seems that the MOSFET is being used to turn the feeder part of the machine on/off.

void dispense_food()
{
  digitalWrite(mosfetPin, HIGH);          //dispense food
  delay(500);

  digitalWrite(mosfetPin, LOW);           //reset feeder switch
  delay(500);
}

On the feeder's listing page, it's noted to use a "28V DC stepper motor." Arduino electronics use around 5V most of the time, I think. (The machine also gets plugged into the wall. )

The people who worked on this before me (and actually built the machine) didn't leave much behind, and are extremely difficult to get in touch with this time of year. But, they did leave a rather old, very sketchy circuit diagram conspicuously labelled "TEMP" in large letters. Not sure if it'll be any help.

Spoiler: Sketchy circuit diagram

 

[(*steve*)]

Let me tell you that the diagram, while terrible, tells me enough

I'll let you do the searching. Once you've done that, post a link to what you've decided and we can check it out.

1. Go to http://Digikey.com
2. In the search field enter "MOSFET" and hit enter.
3. In the list of top results click on "transistors - fets, mosfets - single"
4. This is the parametric search. Look for the heading above the box FBT type and select "N-channel". Near the red button labelled "apply filters" there is a checkbox "in stock". Select that then click "apply filters".
5. You now have a list of all N channel mosfets but we need to narrow that down. Go to to the box headed "drain to source voltage" and at the bottom of that list enter a range of voltages with a minimum of 80 and a maximum of 200. Then click apply filters again.
6. This is a range of n channel mosfet with an appropriate voltage range. Now we need to select a current rating. Go to the box headed "current - continuous drain", scroll down to 8 amps click on that then scroll down to 100 amps hold the shift key and click on that. You're now select a range of between 8 amps and 100 amps. Click on apply filters once again.
7. Now we need to ensure that the MOSFET is in an appropriate type of package. Scroll across until you can see the box labelled "mounting type" and select the mounting type "through hole". Then click on "apply filters"
8. and now we have to select the package itself. Scroll across to the right until you can see the box headed "package / case" and select all packages with the number "220" in them. Hold the ctrl key down to allow multiple selections. Then "apply filters".
9. Now for the most important feature. We need a a logic level mosfet. Find the box headed Drive voltage. Select all rows which start with a value less than or equal to 5 volts. Click on "apply filters" once again.
10. You now have a list of all mosfets which fit your specification. To find the best buy enter the quantity you require in the "enter quantity" boxt and then press the arrow pointing upward under "unit price".

When I did this (with a quantity on 10), I found a remarkable coincidence (I think not) in the part number of the device on the top of the list.

I recommend you buy a few more MOSFETs than you need, just in case.

But let us know what you find.

 

[optogeneticist]

What a search index. I feel like Diogenes walking into a Walmart.

Thank you. You're being a great help.

I'm getting a different number of results than you, though. In step 9, where we select the drive voltage, should I select options in which only one of the numbers is below 5v, or do they have to all be less than/equal to 5v? (e.g. a listing of "4.5v, 10v" - should I select it?)

Also, step 6. There are multiple listings labelled 100v - there's "100v (Ta)", "100v (Tc)", "100v (Tj)" etc. Same with 8v. Should I be including all of these, or just one? If so, which?

 

[optogeneticist]

Also, someone on another website directed me to this product. Does it look right?

 

[(*steve*)]

Also, someone on another website directed me to this product. Does it look right?

That would be fine except they are not in stock

I'm getting a different number of results than you

I didn't tell you how many results I got

In step 9, where we select the drive voltage, should I select options in which only one of the numbers is below 5v, or do they have to all be less than/equal to 5v? (e.g. a listing of "4.5v, 10v" - should I select it?)

The first voltage should be less than or equal to 5V. I think it's the first 5 entries from memory.

Also, step 6. There are multiple listings labelled 100v - there's "100v (Ta)", "100v (Tc)", "100v (Tj)" etc. Same with 8v. Should I be including all of these, or just one? If so, which?

Select from the first 8 to the last 100. It's not too critical though.

You will probably end up looking at this one. But it may depend on where you are. I'm in a small lonely part of the universe. You could be at a college in Portland Oregon for all I know.

 

[Bluejets]

If any help....
I use either IRL3803...30v...0.006 RDS....140A (to220)
Or IRL540N.....100V ...0,044 RDS...36A

Either readily available Ebay or whatever......no too bad a price @ 10 units