Warning- LM317K duds from Digikey

[wraper]

1A current draw does not exceed the specs of an LM317K. And it has nothing to do with circuit quirks either because the Digikey ones failed in both the unit itself as well as on a DC load.

I did not say anything about the current draw as by itself it should not be an issue for a good part.

I think what a couple of people are also missing here is that a genuine LM317 has multiple degrees of protection. So while I was using these as replacements in a circuit that is literally the typical application circuit in the datasheet that we've all seen 10,000 times(!), even if the designer had done something stupid like trying to pull too much current, giving them too much input voltage or inadequate heat sinking a genuine part should go into protection mode. These things appear to go open circuit permanently immediately upon the current draw hitting 1A or so.

It is supposed to have only overcurrent and overtemperature protection. Other than that, it's not hard to kill it.

Third- Digikey provided a refund immediately without requesting returns or more than a one paragraph rundown of what happened. I'd bet dollars to donuts that means it's not the first issue they've had with these.

It has nothing to do with quality of parts. It's just how DK responds to customer complaints.

it's literally the bog standard LM317 circuit seen in every data sheet ever written and about 10 billion products out there. A few caps, a couple resistors and some protection diodes. If you don't know what that circuit looks like you probably shouldn't be in this thread shooting your mouth off.

I know how standard circuit looks like. But I don't have a crystal ball to know what you actually did, what you consider non-inportant and not worth mentioning may be very important to others for finding the failure root cause. And you still did not say input voltage.

[David Aurora]

I think what a couple of people are also missing here is that a genuine LM317 has multiple degrees of protection...... trying to pull too much current, giving them too much input voltage or inadequate heat sinking a genuine part should go into protection mode. These things appear to go open circuit permanently immediately upon the current draw hitting 1A or so.

We're aware of the protection features, but the one thing you have wrong there with protection is including input voltage--that will kill them instantly.  It isn't actually input voltage, it's the difference between input and output that matters.  One way protection functions can fail is when you have an input voltage higher than the maximum but the output voltage is also high enough so that the difference is less than the max.  Assuming that circuit survives startup, it will work fine until one day it overheats or gets overloaded and then right as the regulator either limits current or goes into thermal shutdown the max voltage spec is suddenly exceeded and it pops.  I think that's why the question arose. 

However, I think you just got regulators with the same crappy die that mine had and they went poof in the same manner and for the same reasons.  The input voltage question is mildly interesting because that crappy chip might also go poof at a lower-than-spec voltage differential and still work OK in a lot of circuits.  If you still have your original and fake replacement parts, perhaps peeling the can open and having a look would be interesting as well.

I didn't think I'd need to say this guys, but this isn't my first day at an electronics bench. Jesus Christ. Yes, I understand how to use and how not to use a regulator.

This post wasn't a question about whether or not the designer made a mistake, it was a warning to others not to use what I've confirmed as dud parts in the hopes that it would save someone else some time/money.

The reason I didn't bother including every measurement is because it was of no relevance, everything was already checked before I went blaming parts and found to be well within safe operating areas. And again, the design is a tried and true, very basic LM317 circuit that works in more devices than you can poke a stick at. Nobody is reinventing the wheel here pushing this thing beyond its capabilities.

The finer details about what these parts can take is kind of an interesting side note I guess, but not the point here. The point is that these parts are marked as LM317K parts but break when used well within the safe operating area of an LM317K.

[David Aurora]

If you still have an undamaged device, you may want to drop a line to Noopy, to see if he would be interested in taking some die pictures and compare them against other images of the same device. But different vendor.

That would be cool but all 3 I had failed

[David Aurora]

1A current draw does not exceed the specs of an LM317K. And it has nothing to do with circuit quirks either because the Digikey ones failed in both the unit itself as well as on a DC load.

I did not say anything about the current draw as by itself it should not be an issue for a good part.

I think what a couple of people are also missing here is that a genuine LM317 has multiple degrees of protection. So while I was using these as replacements in a circuit that is literally the typical application circuit in the datasheet that we've all seen 10,000 times(!), even if the designer had done something stupid like trying to pull too much current, giving them too much input voltage or inadequate heat sinking a genuine part should go into protection mode. These things appear to go open circuit permanently immediately upon the current draw hitting 1A or so.

It is supposed to have only overcurrent and overtemperature protection. Other than that, it's not hard to kill it.

Third- Digikey provided a refund immediately without requesting returns or more than a one paragraph rundown of what happened. I'd bet dollars to donuts that means it's not the first issue they've had with these.

It has nothing to do with quality of parts. It's just how DK responds to customer complaints.

it's literally the bog standard LM317 circuit seen in every data sheet ever written and about 10 billion products out there. A few caps, a couple resistors and some protection diodes. If you don't know what that circuit looks like you probably shouldn't be in this thread shooting your mouth off.

I know how standard circuit looks like. But I don't have a crystal ball to know what you actually did, what you consider non-inportant and not worth mentioning may be very important to others for finding the failure root cause. And you still did not say input voltage.

I feel like I'm arguing about whether or not the buoyancy of the toilets played a part in the sinking of the Titanic here.

Again- if there was an issue with the circuitry around it this wouldn't be a thread. I'm not asking for advice, I'm warning others not to trust something I've confirmed to be a dud batch of parts.

[David Aurora]

install a pot in an ADJ, VIN is within rating, Iout is within rating, and you use it normally, and it breaks, then it is either defective, designed that way, or are being stingy to keep it cheap.

curious what kind of die design it is.
if it is the same as the 1117 series, it will have to be broken.
1117 has an image of being easily broken.

This is essentially what I've explained a thousand times now already. In a valid and working design, well within ratings these parts failed. That's the whole point of the post.

[coppercone2]

somehow this thread is starting to feel like

[magic]

These things appear to go open circuit permanently immediately upon the current draw hitting 1A or so.

Can you find any diodes between the input and other pins? Maybe it's simply a bond wire fusing because it was too wimpy.

[wraper]

I feel like I'm arguing about whether or not the buoyancy of the toilets played a part in the sinking of the Titanic here.

I feel like "it's garbage because trust me bro". Why in hell would you withhold even input voltage? I see no plausible reason to do so except it being very close to the max spec or exceeding it.

[thm_w]

If you still have an undamaged device, you may want to drop a line to Noopy, to see if he would be interested in taking some die pictures and compare them against other images of the same device. But different vendor.

Digikey still sells them so you are free to order more, or I can send the funds if someone wants to in depth analyze them.

[David Aurora]

I feel like I'm arguing about whether or not the buoyancy of the toilets played a part in the sinking of the Titanic here.

I feel like "it's garbage because trust me bro". Why in hell would you withhold even input voltage? I see no plausible reason to do so except it being very close to the max spec or exceeding it.

Nobody is "withholding" anything. Can you not read? As stated over and over again, everything was WELL within safe operating areas. If something had been either exceeding ratings or even close to it there would be no thread about this because the explanation would be that the components were being abused.

You seem to have this idea in your head that the designer or myself are shoving some ridiculous voltage into the things, no idea where this assumption comes from or why you're so hell bent on repeating it. Once again- I'm not asking for your input on why the components failed, the answer to that is obvious to anyone with basic reading skills. I'm warning others that these components are failing in completely standard circuits under completely safe conditions according to their specifications in the datasheet. If you're too thick to comprehend this that's your issue.

[wraper]

Is that Vin number under NDA? LMAO  . Apparently explaining actual conditions of failure is too much to ask. I guess plebs like me do not deserve to know anything more than amorphous "WELL within safe operating areas".

[David Aurora]

Is that Vin number under NDA? LMAO 

For real mate- this post was a courtesy warning to other techs. If you don't like it you're absolutely welcome to go fuck yourself.

[David Aurora]

Is that Vin number under NDA? LMAO  . Apparently explaining actual conditions of failure is too much to ask. I guess plebs like me do not deserve to know anything more than amorphous "WELL within safe operating areas".

Oh god, you're doing post edits now after I reply?

Here's the thing- your sarcastic pleb comment actually nails it. You don't seem to be understanding that you truly are an absolute nobody to me. You're just some dude with seventeen fucking thousand posts on an internet forum(!) who has obsessively latched onto a completely irrelevant detail thinking he's cracked a major mystery like Scooby Doo.

What exactly is the payoff you're hoping to get from carrying on barking up the wrong tree for 2 pages? Like do you genuinely think at some point I'm going to suddenly go "Oh shit, wraper was right, I hadn't checked the circuit! Vin was actually 100V/1000/10,000V! What a genius!"? You know, despite having already specified not only that circuit conditions were absolutely not the issue, that 3 out of 3 of the brand in question failed yet none of the alternatives had and that the replacements had been stress tested in the same circuit and were having absolutely no issues. And to top it off, in a classic circuit straight out of the datasheet.

Time for you to get a hobby outside of shitposting I reckon.

[5U4GB]

somehow this thread is starting to feel like

Or this :-).

[David Aurora]

somehow this thread is starting to feel like

Or this :-).

Pretty much.

The whole point of the original post was just to say "Hey, these things have popped up on Digikey replacing out of production parts but be wary because the ones I received were dodgy". I really wasn't expecting a pissing match over having some random guy on here demanding detailed measurements 

[Shock]

Just say they are a chinese reseller, people tend to give you the benefit of the doubt then. The ones that still hold out are anti west shills.

[5U4GB]

The whole point of the original post was just to say "Hey, these things have popped up on Digikey replacing out of production parts but be wary because the ones I received were dodgy". I really wasn't expecting a pissing match over having some random guy on here demanding detailed measurements 

It's his posting style.  Having become aware of the poster's name I've now noticed it in other threads as well, e.g. here (that's the response to the post).

[Psi]

If you still have an undamaged device, you may want to drop a line to Noopy, to see if he would be interested in taking some die pictures and compare them against other images of the same device. But different vendor.

That would be cool but all 3 I had failed

It's a TO3, take a hacksaw to the metal can and lets have a look what's inside

[David Aurora]

If you still have an undamaged device, you may want to drop a line to Noopy, to see if he would be interested in taking some die pictures and compare them against other images of the same device. But different vendor.

That would be cool but all 3 I had failed

It's a TO3, take a hacksaw to the metal can and lets have a look what's inside

Definitely chucking that on the to do list, might even cut it open tomorrow if I get a chance

[Siwastaja]

I really wasn't expecting a pissing match over having some random guy on here demanding detailed measurements 

No one even asked for "detailed measurements" (although those would be helpful too), just the most basic information like a schematic and input voltage. What is so difficult in disclosing them? This is what every sensible engineer would ask for as the very first thing, and that's what the manufacturer is also going to ask when you complain. Now you only made yourself look like a total nutjob and given the extreme arrogance in the way you communicate the issue I have a very strong feeling that it is pretty likely you just did something wrong and the parts are fine.

"Digikey is sending bad parts, trust me bro I did everything right" why should I care?
vs.
"I suspect bad parts, I used them per this schematic, do you see anything wrong in what I did and would you agree that it could be bad parts?"  - and now we are talking.


I mean, if you are an engineer and not some kind of con artist, the very first thing you do upon suspecting bad parts is you do take detailed measurements and ask for second opinion, then work with the manufacturer or distributor (and discuss with peers e.g. on a forum like this), but now it seems you are here just to vent and throw temper tantrums?

[nctnico]

Buying parts from a reputable vendor doesn't mean they are good. Personally I avoid the Multicomp and RS-pro branded parts from Farnell and RS as these are rather crappy. I can buy better quality from Aliexpress. And then there are shady semiconductor manufacturers like Sipex which make devices which fail within a year. Likely EVVO is a similar manufacturer. Given the data David has provided the LM317K he bought are obviously fake. At least the thermal protection should have kicked in. The low price is also a bit of a giveaway. Paying less than US$10 for a highly antiquated part is a red flag.

[David Aurora]

I really wasn't expecting a pissing match over having some random guy on here demanding detailed measurements 

No one even asked for "detailed measurements" (although those would be helpful too), just the most basic information like a schematic and input voltage. What is so difficult in disclosing them? This is what every sensible engineer would ask for as the very first thing, and that's what the manufacturer is also going to ask when you complain. Now you only made yourself look like a total nutjob and given the extreme arrogance in the way you communicate the issue I have a very strong feeling that it is pretty likely you just did something wrong and the parts are fine.

"Digikey is sending bad parts, trust me bro I did everything right" why should I care?
vs.
"I suspect bad parts, I used them per this schematic, do you see anything wrong in what I did and would you agree that it could be bad parts?"  - and now we are talking.


I mean, if you are an engineer and not some kind of con artist, the very first thing you do upon suspecting bad parts is you do take detailed measurements and ask for second opinion, then work with the manufacturer or distributor (and discuss with peers e.g. on a forum like this), but now it seems you are here just to vent and throw temper tantrums?

Who am I supposed to be asking for a second opinion here? You? Wraper? I don't know who either of you are or whether you know your ass from your elbow, why would I feel the need to run measurements past you before posting a warning that I received some bad parts? As I've said earlier, I took measurements as soon as I noticed an issue and that led me to suspect bad parts, I was able to reproduce the issue multiple times, and reported the issue to Digikey before posting here. Did you actually read any posts in this thread before deciding to chime in? The original post literally says all of this.

Yet again for the slow kids:
- The circuit is straight out of any LM317 datasheet out there, you're welcome to look it up if you're so inexperienced that you can't immediately visualise it. Diode for diode, resistor for resistor, it's the same damn circuit you'll find in about a million power supplies out there.
- This is a repair job, not a design job. The old regulator worked for decades and it didn't die on its own (the owner was attempting DIY work and killed it). The new regulator works absolutely fine (even when stress tested much harder than the actual circuit requires). 3 out of 3 of the regulators from Digikey failed, one in circuit and two while testing the supply with a DC load. All failed instantly once current draw reached 1A or so (and I do mean instantly, not a single one of these things lived more than about a minute including the time they were being tested at 100mA/500mA/etc).
- There is no big secret or grand conspiracy about the circuit details. The voltage differential is something like 8 volts for fucks sake (25V or so in for 17V out), hence why I've said over and over again that everything was running well within safe operating areas. Would you also like to know exact heatsink temperature even though we know it didn't overheat? Current down to the uA even though we know current limit wasn't exceeded? Should we go back and check moon phase? Do you want to know what I had for lunch that day?
- The post was a courtesy warning about parts failing when they shouldn't be, not a request for a multi page chat about it. If you don't believe me and think the parts are fine then go use them. Best of luck with that.