The Importance of Verifying MOSFETs and Op-Amps: A Cautionary Tale

As any electronics enthusiast knows, verifying the authenticity and performance of components is crucial when it comes to ensuring the reliability and safety of electronic devices. In this article, we will delve into the world of MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and Op-Amps (Operational Amplifiers), two common components used in a wide range of applications.

When it comes to verifying the authenticity of MOSFETs, it's not just about checking the packaging or labeling. As we'll see, even seemingly identical-looking components can have significant differences in terms of performance. In this video, our host examines a pair of MOSFETs that may or may not be authentic, and puts them through a series of tests to determine their true nature.

First, let's take a look at the packaging of these two MOSFETs. As we can see from the label, they are both described as "MOSFETs" with the same type number (IRLZ34NM). However, upon closer inspection, we notice that the fonts used on each component are slightly different, and the design of the heatsink is also distinct. This suggests that these two components may not be identical after all.

According to the manufacturer's datasheet, the first MOSFET has a resistance of 5mΩ, while the second MOSFET has a resistance of 350mΩ - nearly seven times higher than its advertised value. This significant difference in performance is a clear indication that one of these components is likely fake.

But what does this mean for our electronics projects? In many cases, the difference between a genuine and counterfeit component may not be immediately apparent, especially if you're using a pre-assembled module or a low-cost substitute. However, as we'll see in the next section, even seemingly minor discrepancies can have significant effects on the performance of your project.

Op-Amps: A Comparison of Authenticity

Op-Amps are another common component used in electronic devices, and their authenticity is equally important when it comes to ensuring reliability and safety. In this article, we'll examine a pair of Op-Amps that may or may not be authentic, and put them through a series of tests to determine their true nature.

The first Op-Amp in question is the LM358, a popular choice for a wide range of applications. However, when we compare it to another LM358 component, we notice some subtle differences. The first component has an input offset voltage of around 13mV, while the second component has an input offset voltage of 160mV - more than 12 times higher.

Similarly, the slew rate of the two Op-Amps differs significantly. According to the datasheet, the LM358 should have a slew rate of 0.3 V/μs, but the first component we tested has a slew rate that is nearly twice as fast. The second component, on the other hand, has a slew rate that is significantly slower than expected.

What does this mean for our electronics projects? In many cases, the difference between an authentic and counterfeit Op-Amp may not be immediately apparent, especially if you're using a pre-assembled module or a low-cost substitute. However, as we'll see in the next section, even seemingly minor discrepancies can have significant effects on the performance of your project.

The Importance of Testing Components

When it comes to verifying the authenticity and performance of components, testing is key. In this article, we've seen how simple tests such as measuring resistance and slew rate can reveal significant differences between genuine and counterfeit components.

However, there are many other types of tests that can be used to verify component authenticity, including visual inspections, electrical testing, and even chemical testing (in some cases). The most important thing is to approach these tests with a critical eye and a healthy dose of skepticism - after all, as we've seen in this article, it's not uncommon for counterfeit components to masquerade as authentic.

Conclusion

In conclusion, verifying the authenticity and performance of MOSFETs and Op-Amps is crucial when it comes to ensuring the reliability and safety of electronic devices. While these components may seem like minor details, even small discrepancies can have significant effects on the performance of your project.

As we've seen in this article, testing is key to verifying component authenticity. By approaching these tests with a critical eye and a healthy dose of skepticism, you can ensure that your electronics projects are reliable, safe, and perform at their best. So the next time you're working on an electronics project, remember to always verify the authenticity of your components - it's worth it in the end!

WEBVTTKind: captionsLanguage: enThis right here is a MOSFET and this righthere is another MOSFET of the same type, atleast according to its label.Because if we look closely we can not onlysee differences in the font but also in thedesign of the heatsink.And according to the manufacturers datasheetit seems like this one is a genuine one becauseI also bought it from a well known componentsupplier for kind of a high price.But if you love a good bargain like me thenyou probably also already bought a pack of5 of them for the price of 2 originals onesfrom sites like Ebay.With such deals there is always the suspicionthat the components are fake aka counterfeitwhich is a nowadays a big problem when itcomes to electronics.Because as you would naturally assume fakecomponents usually either come with differencesconcerning their properties, they fail quickeror they do not work at all.And since that can be problematic if for examplea fake component has to fulfill a crucialjob in a very important electronics system,I wanted to find out by myself how much suchfake components really suck in comparisonto the originals and that is exactly whatI will be doing in this video.So let's get started!This video is sponsored by Keysight and theirbiggest test gear event of the year Keysightlive from the lab which is now available ondemand.You can sit down with engineering pros aswell as tech YouTubers like ElectroBoom, TheSignal Path, CuriousMarc or even me.Topics range from oscilloscopes to 5G andmuch more so there is something for everyone.So check out the link in the description andlevel up your lab skills.Now before I get to compare the genuine MOSFETwith the maybe fake one of which I probablyhave a few dozen of different types lyingaround as well as having a closer look atmaybe fake Operation Amplifier ICs; Let'sfirstly answer the question how such fakecomponents come to be.Because producing ICs aka Integrated Circuitsor MOSFETs is not really simple.You need a silicon wafer onto which transistorsget formed as well as additional layers forthe wiring and much much more.Just read this MOSFET manufacturing descriptionfound by Google and you know it is not aneasy process.So obviously fake component producers do notgo through this manufacturing process butinstead either refurbish or relabel old salvagedcomponents, simply label empty packages thatnot work at all or what I think is most popularis that they take cheaper worse performingcomponents and relabel them.Through those methods they avoid research,manufacturing and marketing costs and basicallymake a profit selling sometimes garbage.Now to identify fakes we could have a peekat the die inside the IC but since that isnot realizable for most people watching, wecould also look out for package anomaliesor simply do some electrical testing.And exactly that bring us back to my MOSFETsfor which I want to determine their resistancewhen fully turned on and the time it takesfor them to turn on and off because I thinkthose are two of the most important characteristicswhen using MOSFETs in demanding applicationslike a power supply.Now the datasheet states a resistance of 35mΩas well as the values for all the rise andfall times in ns.But before verifying those I would alwaysrecommend pulling out the transistor testerthat you can get for cheap from the internet.With it we can measure some basic values ofthe original MOSFET that we can then compareto the maybe fake one.And it seems like all the recorded valuesare pretty close to one another.So time for the proper resistance test inwhich I powered the gate with 12V and leta constant current of 1A flow through theMOSFETs while measuring the voltage drop acrossthe drain source path.The original one came with a voltage dropof 25mV and unexpectedly the fake one alsooffered pretty much the same voltage meaningthe resistance of both MOSFETs were accordingto the datasheet.So next I soldered load resistors to bothMOSFETs which get powered with 12V while asquare wave signal with a high frequency getsapplied to the gates through the help of twoMOSFET drivers.And after inspecting the occurring waveformsat both MOSFETs on the oscilloscope it seemslike once again there isn't really much ofa difference.Their rise and fall times also correspondwith the datasheet so is the maybe fake MOSFETan original one instead?Well you can never be 100% sure because thereare tons of other tests we would have to doto truly find that out.Only one thing is for sure, ordering partsfrom Ebay or similar is like a box of chocolates,you never know what you are gonna get.For example I had another batch of IRLZ34NMOSFETs lying around which I also simultaneouslytested and as it turns out their resistanceis 5mΩ lower than the original one and theyalso turn off a bit quicker.So yeah this maybe fake one is better butthen again you can also accidentally receivesuch an IRF540 MOSFET fake which in my casecomes with a resistance of around 350mΩ whichis 4.5 times higher than its advertised resistance.Like I said Ebay purchases are a gamble butonly there you can save a bit of money orfind such handy to have assortment sets whichI truly love to have around.This one comes with a variety of OpAmps whichis a component that I use quite often in projectsfor different applications.So of course I want them to work properlyand just by having a look at the LM358 onesI feel like something is off here in comparisonto an original 358 I once again got from abig supplier.And since I also had another LM358 lying aroundwhich again looked a bit different I thoughtthis comparison could be fun.So what I want to compare is their input offsetvoltage as well their slew rate.According to the datasheet the input offsetvoltage is 3 to 7mV which describes the voltagedifference between the inputs of the Op-ampthat when amplifying a signal also gets amplifiedand thus is basically a divergence to theideal output value which means we want thisoffset voltage to be as small as possible.And the slew rate according to the datasheetis 0.3 V/us which describes how fast the outputof the Op-amp rises and falls and that isobviously important for fast signals.Now for the input offset measuring I simplybuilt up an inverting op-amp configurationwith a gain of 100 whose input I connectedto GND.So by measuring the output voltage we knowthe offset voltage multiplied by 100 whichin the case of the original LM358 is around13mV.The other two came with values of 160mV and70mV which is all still in spec with the datasheetbut you can already see that there is a noticeabledifference.So next was the slew rate test for which Isimply build up a voltage follower circuitfor all the Op-amps on a breadboard.The input signal is like before with the MOSFETsa square wave and after applying that to allthe Op-amps we can have a look at all theoutputs at the same time.Now feel free to guess which Op-amp you thinkis the original one and let me stop you rightthere it is not the fastest one because thatis the maybe fake from the assortment set.Instead it is the second best performing onewhile the slowest one is the other maybe fake.So once again the maybe fake options didn'tperform terrible since they all fulfilledthe datasheet requirements I tested.But like I said before don't get too comfortablewith questionable components because it canalso be a complete nightmare working withthose.But I am not really the role model here sinceI have used maybe fake components in the pastand will probably use them in the future.All I wanted to do with this video is raiseawareness and I hope I did just that.With that being said I hope you enjoyed thevideo.If so consider supporting me through Patreon.As always don't forget to like, share, subscribeand hit the notification bell.Stay creative and I will see you next time.