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FastTech's AMC7135 "Advanced +" IC's ???

jimdt7

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Hello guys,
Two months ago I ordered some AMC7135 chips from Fastech (both 350mA and 380mA), when they arrived I put them to test only to find out that they were cheap knock-offs with almost 1.2V drop. I contacted them and they offered to send me replacements. Yesterday I received the new chips, sadly I didn't have time to test them yet, but two things intrigued me. First of all the 350mA chips came in a small zip bag and not inside a black reel, apart from that when I read the letter that came with the chips I saw that it said "Advanced +" next to the chips. Maybe they have two batches of AMC's...I dunno...! :undecided:



Thanks for reading! :beer:
Jim
 
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crazyspaz

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hmmm...Guess that means i need to check the chips i got (got the same thing as you). although i dont remember if mine said "advanced" or not. Dont think they did.
 

Benm

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It doesn't really matter what it is described as. A real, original AMC7135 (produced by Addtek) shoud sink 340 to 380 mA at a dropout voltage of no more than 200 mV. Typical values are 360 mA and a dropout of 120 mV.

There is one exception, the so called 'rank A' version of the addtek amc7135 that output a slightly lower current (320 typical), but has the same low drop out.

Any chip with a different current or dropout is NOT an amc7315. It could be a fake, or re-labeled chip etc... but it is not the real deal and you should not accept receiving such items when you order an amc7135 from any source.

As far as packging goes: that can be anything: the come in reels (of 5000 pcs) out of the factory, so if you order single chips they must be repackaged. This would usually be an anti-static bag, but that isn't really required for this chip so it could be an ordinary ziplock. Some resellers just cut a piece out of the reel, though that's not always possible (you tend dislodge one chip when you cut up a real).
 
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ryansoh3

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I'm pretty sure the "Advanced +" came from the fact that the chips are labeled as "AMC7135 350mA Advanced Current Regulators - SOT-89 (100-Pack)" and FT just cuts off the words and replaces it with a "+" just like the LED Flashlight driver.
 

jimdt7

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Based on some tests I made yesterday, they seem to have the same characteristics as the old ones. (~1.2V dropout). I'll try to get my hands on the Original Addtek chips and compare them once and for all! Thank you very much for the info Ben! :beer:

Have a nice day guys,
Jim
 

benmwv

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How are you testing the dropout?

Im asking because linear current regulators really only have a minimum dropout. They almost always drop more than that in use, since this is how they regulate current with changing input and output voltages. Basically they drop as much voltage (within reason) as they have to all the way down to the minimum dropout to keep the current flow at the set level.

So if you are giving it any more voltage than it needs it will drop that voltage, and that means it is working correctly.

Im not saying these couldnt be faulty, but it seems logical to me that you would be using a 3v led or diode and a fully charged battery giving you ~1.2v dropout on the regulator.
 
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jimdt7

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Here is how I test them:
ADJ Power Supply in CV mode ----> AMC7135 ----> TestLoad set at ~3V drop ----> Multimeter.
In order to get ~350mA I have to set my power supply to 5V! :thinking:
Any ideas?
EDIT: I tested them again using a Sanyo battery fully charged at 4.19V...with 3V drop I am only getting 240mA. I also tried putting a capacitor between input and ic...no changes at all...

Jim
 
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Benm

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Seems to be a good way to test them indeed.

As i said, these chips are not AMC7135 and you should insist on a refund from however sold you these things (no idea what they are, but not what your ordered). You may also alert addtek that someone is selling counterfaits. I'm sure they are aware of that, but giving them a source that acutally ships these could help to identify their source and stop them coming onto the market.
 

benmwv

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Yeah, I totally agree. I don't see any problem with your testing so these are obviously fake chips. It's a shame people are selling these.

I've had good luck buying them on ebay before, but these fake chips are probably all over ebay now too.
 

jimdt7

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I sent an email to FastTech asking for a refund...we'll see! :beer:
Thank you for your help guys! :D

Have a nice day,
Jim
 

Benm

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Oh yeah, beware of it - popular components are often forged with various quality.

It has been a problem for many years, the fact that this now concerns a laser driver might be novel, but fake components are found in many categories. In some cases they function perfectly well but have just been manufactured without paying for patents and such, but in some cases they are clearly inferior products that will fail in practical application. Take a look at these forged transistors: Counterfeit Transistors

In some cases the damage can go very well beyond only blowing out the fake component - a fake driver chip could blow a laser diode, or a fake transistor could blow out a very expensive speaker system if one shorted out (applying DC to the output).
 

BShanahan14rulz

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These inexpensive regulators are often used in 1 cell flashlights. Doing a simple ali search for flashlight shows that there are thousands of variants of flashlights. I can see these companies finding the lowest cost chip that says amc7135 and using that. Because an underpowered LED flashlight will still be amazingly bright compared to your old 2xD-cell plastic dollar store flashlight, even if it's only being driven at 480mA rather than the 700mA advertised.

It IS sad to see that there are counterfeit regulator chips. Not to be rude, but I was hoping that you were one of those people who is still learning to use a multimeter. I'm glad you aren't, mind you, but 'tis a sad day to see fake AMC7135.
 

grainde

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Damn, I just bought a couple of reels of 10 chips from FT. The first mod I did with them didnt work and I had put that down to the driver. Guess Ill have to test the individual chips now...:( :beer:
 

Benm

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It IS sad to see that there are counterfeit regulator chips. Not to be rude, but I was hoping that you were one of those people who is still learning to use a multimeter.
What good is a multimeter here? Its kinda hard to take measurements before they actually arrive - and then you find out you have been scammed.

Using a dummy load you'll probably figure out if you have the real chip or a counterfeit, but at that point it's probably too late to do something about it, except leaving very negative feedback if you bought it ebay.
 
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Old 5-6 digit Fluke meters can be had fairly cheap. They're usually years out of calibration, so figure
another $150 for a cal if you want a truly accurate measurement.
 

Benm

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I didn't mean that the multimeter wasnt performing well - i'm quite sure most are, even very cheap models get 2% accuracy or better.

The problem is that you only get to use it once your chips have arrived, and if you find them faulty at that point, there is little you can do. Considering their price sending them back for a refund when you pay for return shipping often not viable.
 




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