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Playing with IC’s: Part 2

By on May 19, 2015
playing with ic











ic repair

In my previous article, “Playing with IC’s”, I was checking the Fiti #FR9882 IC to see if it may have been the cause of the Cisco router quitting on us. The IC is an 18V 2A 340KHz Synchronous Step-Down DC/DC Converter (SOP-8). For a 3.3V output, the input can be between 5 – 12V. Even when I used a 4.5V input, the IC had an output of a tad over 4V. And when I raised the voltage up to 12V, the IC blew. According to the datasheet the IC should handle 18V and currents up to 2A. My Power Supply was set to a 0.5A max to limit the current.

Here is the Datasheet:

 fr9882 datasheet

So I bought some new IC’s from a Chinese company on AliExpress and they finally got here. They were not mailed in ESD protective packaging or with any ESD protection at all, so I don’t know if they are even good IC’s. They were just thrown into a small plain plastic baggie. I don’t know if I’ll ever buy anything from them again.


But we will see if any of the IC’s are good. According to the Datasheet, the IC should output 3.3V with an input of between 5 – 12V when set up as the top schematic on page 2. My breadboard is set up to the top schematic, and now I also have a 26.1K 1% resistor for R1 that the schematic calls for. So I don’t have to use the 82K & 39K resistors in parallel like I did in the first article. Everything else is the same as the first article – except the IC, of course.

 ic from aliexpress

I believe I’m just wasting my time with these IC’s, but I will go ahead and try them in the hopes that at least one of them survived.

 ic repairing

As you can see in the photo, the 26.1K 1% Resistor is well within specs.

Here are a couple photos of me setting up the breadboard.

ic set up breadboard

ic breadboard

The new IC is on the breadboard. It would be better to put the circuit on a proper PCB, but the breadboard should be ok to test the IC.

This time I’m going to start off with a 5V input and limit the max current to 0.5A. Since we are only lighting an LED in this circuit, 0.5A should be good enough for the IC to work properly and keep the current lower in case of a short or some other problem. Knowing how the IC’s were shipped to me, there is no telling what will happen when I apply power to the IC. According to the schematic in the Datasheet, the IC should output 3.3V. I will be using my new Uni-T UT-139C DMM to measure the supply voltage to the input of the IC, and measure the voltage of the IC output with my Fluke 87V.


The IC was outputting about 3.4V and the LED was lit, and before I could get the camera and take a photo, it stopped working! I didn’t hear a pop or anything. I don’t know if the IC was bad, got hit with static electricity during shipment, or if I hooked something up wrong. I looked the breadboard over good and couldn’t find anything arcing. Everything was connected correctly also.

I hope that there is at least one IC in the bag that is good. Soldering all the leads to them all is just too much trouble. So I ordered some tiny breakout boards from SparkFun for the IC. It will be a lot easier to work with and less heat transfer to the IC pins. Swapping IC’s will be much easier and less stress on the pins.

ic helping hand


The breakout board is on the breadboard and it has continuity to the pins. So, all is well – so far. I removed the switch from the circuit to make things easier.


As you can see in the photos, the breakout board is on the breadboard and the IC is only outputting around 2.28V. Raising the input voltage raises the output voltage. I decided to try another IC and see what it will output.


I changed the IC with another one and it is outputting 2.16V. I started thinking that maybe one LED was not enough load for the IC. So I added some more LED’s because I don’t have an electronic load to use.


That didn’t work either. So I started experimenting with different caps with different capacitances with not much change in output at all. I also started adding various caps for the optional caps that are marked C7 & C8 on the schematic, with no luck.

I decided to remove the IC from the breakout board and solder on another one. Because of the way the IC’s were shipped to me, it is possible that they were all damaged and I’m just wasting my time. But I have 7 left so I may as well try them and hope that one of them will work like the datasheet says it should. Of course I don’t expect them to output a perfect 3.3V on a breadboard, but it should be close enough to test.

 led breadboard

Here is a picture of the LED board.


This is actually the 5th IC. I forgot to take a photo of the last IC, but it was only outputting about 0.8V and I removed it straight away. As you can see in this photo, the IC is only outputting about 13mA. I double checked the continuity from the breadboard away from the breakout board pins to the top of the pins of the IC’s to make sure I didn’t get any false readings, and the continuity is good. You can see it in the next photo. I double checked all connections also and everything is good – it has to be the IC’s that are the problem. I also added the 1N4148 diode, D1 in the Fig.3 schematic, and it made no difference. The datasheet says it needs to be in the circuit as an external boost diode when using an input of 5V to help improve the efficiency. I left it in the circuit even though it seemed to make no difference.

It’s not looking good folks: but usually luck would have it that the last IC might be the good one. It would be nice for this experiment if at least one of them survived shipment.



This is the 6th IC and you can see it outputting only 115mA. The boost diode is still in the circuit. Changing caps doesn’t make much difference. I also dropped the load back to one LED with not much change in the output of the IC.


This is the 7th IC. Changing caps and the aforementioned changes didn’t make enough difference to the output to matter. Of course, I rechecked continuity to the IC pins and connections, and all was good. I will check the last 3 IC’s after I have gotten some rest.


I’ll just skip to the last IC. As you can see it is not working right either. I believe the IC’s are damaged. If the problem was just that the IC’s were on a breadboard instead of a PCB, you would think their outputs would at least be consistent. But they were all over the place – some outputting mA’s, some around 1V, and a few about 4V.


I started turning up the input voltage to see what the last IC would do and the output started rising. Then it shorted around 10V and the Amps on the power supply jumped up to the max setting of 0.48A as you can see in the next photo.

 ic was getting hot

After I took this photo the IC was getting hot, so I removed the power from the circuit and decided to end the article. Sometimes things just don’t work out. If the shipper would have protected the IC’s in ESD packaging, It would have made for a better article – that’s what I believe anyway.

robert calk











Robert Calk is a hobbyist from the USA that loves learning electronics and device repair.

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  1. Bernie Scott

    May 19, 2015 at 11:59 pm

    Well Robert...I have to gave it your best went through the trouble to check every single one of them....and you documented everything along the you stated, your readings were all over the place.......either the data sheet is wrong, (highly unlikely but possible), or, the IC's that were shipped in are defective in various ways that can't be readily seen.....maybe because of the way they were packaged....either thing is for learned quite a lot from this experiment.....and so did I......Thank you very much for the info....It is greatly appreciated......

    • Robert Calk

      May 20, 2015 at 10:31 am

      Thanks Bernie. It is the first time anyone ever shipped IC's to me without any ESD protection.

  2. Steve Jenkins

    May 20, 2015 at 12:08 am

    I think that Robert's issue with the "FR9882 IC" is not due to static damaged components rather than with they way he is testing them.

    This convertor IC, like most of this type, a very critical of the PCB layout of the components relative to the IC's pins.

    There is quite a lot of information on page 10 of the datasheet that explains how important it is for the correct physical location of many of the supporting components.

    If these locations are not adhered to the device's performance and stability are dramatically affected.

    Hope this information helps Robert not to just throw away what could be perfectly useable devices.

    Steve Jenkins

    • Robert Calk

      May 20, 2015 at 10:36 am

      Hi Steve. Yeah I read that, but if that is the case, why are the outputs so much different and not all close to being the same voltage? If they would have protected the IC's in anti-static protection during shipment, then I could at least rule that out as being the problem.

  3. Andre Gopee

    May 20, 2015 at 12:39 am

    Hi Robert, Nice article... maybe you can try another shipper. I usually buy from Mingjiada (HK) Industrial Co. Ltd in China and they ship everything in ESD bags and I am 100% satisfied with them. The person I deal with is Yolanda Lee. Maybe you can try them. Let me know if your interested I will give you her email. Anyway I like your work and keep it up. Hope you get better result next time.

    • Robert Calk

      May 20, 2015 at 10:43 am

      Thanks Andre. I almost abandoned the whole thing just because of the way the IC's were shipped to me. I will give them a try and see what happens since the IC's are not very expensive.

    • Robert Calk

      May 20, 2015 at 11:32 am

      Yes please, I would like to have their email.

  4. Yogesh Panchal

    May 20, 2015 at 12:40 am

    Good effort to find culprit .

    • Robert Calk

      May 20, 2015 at 10:45 am

      Thanks Yogesh.

  5. Albert

    May 20, 2015 at 1:06 am

    Hi Robert, I now see what you mean with 'trouble' with the second part after your previous article.

    I guess you did have ESD failured chips from AliExpress. I never bought from them before because PayPal isn't possible. So my friends and I use Ebay instead.

    At least we did get another look on your Electronic Equipment you use at home. And it is not always about analoge measurements. I myself think those are from the past just like the Slide Rule opposite the Electronic Calculator.

    One question? The coil on the breadboard with marking '100' is no 10uH coil as in the top datasheet circuit? Or is it?

    By-the-way I do not use those solderboards like mentioned ones from SparkFun or others anymore, to test and program for instance those 8 soic BIOS chips. I use SOIC8 SOP8 to DIP8 adapter socket converters. And very cheap on Ebay :

    Maybe something you also could use on your breadboards when doing these tests? No soldering required and quick insertion.

    Maybe you could do this test again with some parts from Ebay? I can't believe that parts are so badly shipped that none from 10 parts work...


    • Robert Calk

      May 20, 2015 at 10:59 am

      Thanks Albert, I appreciate your input and tips. As I mentioned in the article, the first IC I tried was outputting 3.4V only for about 3 seconds. By the time I grabbed my camera to take a photo, the IC blew and output went to almost zero. It was the only IC that was close to the expected output.
      I couldn't find the IC's on Ebay. Thanks for the tip on the adapter socket converters - I will definitely order some.
      Yes the inductor is 10uH. I rewound it myself and checked it to make sure it would not be a problem. I believe a picture of it is in the first article.

      • Albert

        May 22, 2015 at 7:38 am

        By-the-way Robert.... I read - if I'm not mistaken - somewhere that you said you are very pleased with your HAKKO 808 desoldering tool ? And buying them should be affordable to ?

        But sadly I saw on Ebay that they aren't sold anymore and replaced by Hakko FR300-05/P (FR-300) Handheld Desolder Gun Through Hole. Which replaces 808-KIT/P for a not very affordable price of $305.99 =>
        New Hakko Model, FR300-05/P De-soldering gun with Carry Case. Hakko Model Number FR300-05/P Desoldering Gun Kit. This new desoldering gun from Hakko replaces the 808-KIT/P (808) that has been the deso...
        I was interested until I heard the price of the new Tool.


        • Robert Calk

          May 22, 2015 at 12:42 pm

          I don't know, I bought mine a year or so ago. I heard that they have a European model 809 but I'm not sure what the price is. You may be able to find a good used one on Ebay pretty cheap. I hear that other companies make decent ones that are inexpensive.
          My 808 was about $150US when I bought it.

          • Albert van Bemmelen

            May 22, 2015 at 8:36 pm

            Thanks Robert, Ebay sells these used 809 desolder guns but as I noticed you need a Vacuum pump too and that is not included. And shipping cost from USA about $25 or more.
            But since you are satisfied with this product I will search for such a tool. I normally still use the old fashioned manual Handheld Tin suck pump but it isn't handy I guess.

            • Robert Calk

              May 25, 2015 at 8:20 am

              Hi Albert. I have the old fashioned ones also but they are no way near as handy as my Hakko 808. The vacuum pump is built into the de-soldering gun. I have no idea what you are talking about it not being included - sounds like a fake 808 to me.

    • Frank Seldevig

      May 20, 2015 at 7:39 pm

      Good work Robert, and thanks for sharing.
      These ICs are not really static sensitive, but would you buy a piece of meat in the supermarket if someone else had touched it?
      Some companies even send capacitors and resistors in anti-static bags. Just a nice professional touch. I would actually give the company a hard time for sending any chip in just a PVC bag.
      Reading an Inductor is like the colour bands on a resistor.
      First two numbers "10" is in uH and the 3rd is the multiplier, and thats 0, so it is 10 uH as specified. I would say its near impossible to do this work with meters alone, without quickly probing with a scope to see what is going on.
      I think the real problem is the grounding of the PAD.
      "GND 4 Ground Pin. Connect this pin to exposed pad." This is from the datasheet. For information I am currently working with LTC3114 and Mohammed Kasims comment apply so much since its 1-2MHz. At 300-400 KHz it is not so important.
      Keep those articles comming.
      Good read 🙂

      • Robert Calk

        May 20, 2015 at 11:07 pm

        Thanks Frank. I was hoping that wouldn't matter. The original IC I took off of the router PCB didn't have an exposed pad, but they sent me the ones that did. Since I was only testing them at low current, I didn't think I needed to worry about thermal concerns. I will try them both ways next time.
        The output of the IC's was only around 60HZ. I didn't think it mattered to mention it.

  6. Mohammed Kasim

    May 20, 2015 at 1:12 am

    Good experiment. You may check that there are some design requirements like the pads(GND) of the ic needs to be grounded, capacitor placement very near to ic pins and its esr value, feedback resistance connection very nearer to ic pins, etc. The best method is to place the Ics on actual PCBs for testing

    • Robert Calk

      May 20, 2015 at 11:04 am

      Thanks Mohammed. Yes, a PCB would be much better. If I make a Part 3, I will test the circuit on both, a PCB and also my breadboard circuit.

  7. Lee

    May 20, 2015 at 1:14 am

    Thanks Robert,
    It's very frustrating... how long have you waited for the shipment ?

    • Robert Calk

      May 20, 2015 at 11:12 am

      Thanks Lee. It took one month to get the IC's. Yes it is frustrating. If they would have protected the IC's, and the output voltages were close to each other, then I would figure the breadboard was the problem and built the circuit on a PCB.
      If I can get some good IC's in good anti-static protection from the supplier that our friend Albert suggested, then I will test them together against the ones I used in this article on both my breadboard circuit and also a PCB.

      • Robert Calk

        May 20, 2015 at 11:30 am

        Oops sorry. It was Andre that gave me the supplier for the new IC's. Sorry Andre.

  8. Mark

    May 20, 2015 at 5:17 am

    Hey Robert,

    Thanks very much for your article. I must admit I do struggle a bit with IC testing. I guess your article only highlights that to get quality products, you have to pay a little more. It is a hard choice to make.
    I would love a book to guide me thru the IC testing process, so that I can get my head around them a little better.
    Thanks to your article, I feel I would have a bit more confidence when trying to diagnose an IC.

    • Robert Calk

      May 20, 2015 at 11:23 am

      Thanks Mark. I'm glad you like the article. From now on when I want to test an IC, I'll build the circuit on a PCB also. I figured that if the breadboard was the problem that the output voltages would at least be similar and not all over the place. But maybe the breadboard makes the IC's do strange things and effect different IC's of the same type differently?
      I have decided to continue the experiment. I will order new IC's and build the same circuit on a PCB also and do some more testing.

  9. mahmoud_tajpour

    May 20, 2015 at 6:19 am

    Hi dear Robert congratulation you are real researcher iam Iranian and iam repair now ihave to say the big problem we have here is the bad components are imported from China.unfortunately the 10pieces of TR.or ics maybe 2or3 of them they work do these problem makes us hard.thanks a lot I will be happy you see in IRAN.

    • Robert Calk

      May 20, 2015 at 11:27 am

      Thanks Mahmoud, I'm glad you enjoyed the article. I will order some IC's from another supplier and test them against each other and see for sure.

  10. Anthony

    May 20, 2015 at 7:08 am

    Hi Robert,
    Most people would give up at least halfway through but you have the tenacity of purpose to see it through,
    because like me you don't want to be laying in your bed at night thinking "what if" ! In electronics it seems
    that there will always be the easy straight forward repairs and the ones where you want to tear your hair out !

    But as usual Robert, great work by you !


    • Robert Calk

      May 20, 2015 at 12:12 pm

      Thanks Anthony. Lol, yes you are right about staying awake wondering "what if?", I am the same way!
      I have heard many experienced people say that they hope our projects "do not" work as expected. That's when we learn more when we start searching for why something doesn't work as planned.

  11. beh

    May 20, 2015 at 11:15 am

    Hi Robert
    Thanks for article and all of your efforts. But if you buy same ic from another manufacturer and more expensive ones you will reach to the result .since there is no any international organization For standardize the manufacturers of electronics components just the price of components in the market determine the quality of the component more expensive means better quality buy more expensive same model from anther manufacturer for sure with better shipment services your goal will achieved.

    • Robert Calk

      May 20, 2015 at 12:22 pm

      Thanks Beh, but they shouldn't sell IC's if they are not going to protect them in ESD packaging. And Aliexpress should remove them from their website. It just makes me not trust any company on Aliexpress!

      • beh

        May 20, 2015 at 6:25 pm

        yes you have the right . but i have heard that in china you can buy ic s or other electronics component by their weight for example: one kilo ic or one kilo other components like resistor etc. of course these kind of components are not tested after production and they are very very cheap yes this is the china!and
        that is why they sent you those ic s with that shape !

        • Robert Calk

          May 20, 2015 at 11:11 pm

          They really were not that cheap as far as IC's are concerned.

  12. Gerald

    May 20, 2015 at 11:59 am

    Hi Robert,
    Having fun I can see 🙂 I admire your perseverance, congratulations.

    By the way, did you check the continuity of your ground rail. I had some of those proto-boards in which the continuity was interrupted at the places where the holes are missing, even though the blue line is continuous.


    • Robert Calk

      May 20, 2015 at 12:30 pm

      Thanks Gerald. I try to have fun while learning! Yes, I checked the continuity on every pin, 2 or 3 times with every IC. I also used the UT 139C for the continuity checks because it only outputs 1.005V.

  13. Frank Seldevig

    May 20, 2015 at 7:48 pm

    Please Robert.
    Try one last try with one of the chips (if you havent hit them with a hammer already :-)) and connect the pad underneath to ground and post what happens.
    I am actually getting excited now :-).

    • Robert Calk

      May 20, 2015 at 11:17 pm

      I understood the principle reason for the exposed pad is for thermal concerns. Testing the IC at low voltage and current should not be a concern on thermal issues. I will check it out when I get some new IC's. And I will compare them to the IC's I used in this article because I still have them. I didn't smash them with a hammer. lol

      • Frank Seldevig

        May 21, 2015 at 8:34 am

        The exposed pads in most of these kind of chips are the ground plane for the internal MOSFETs. It certainly also serve a thermal purpose, and without some form of cooling the chips internal linear regulator plus the mosfet drivers will produce sufficient heat for a thermal shut down. I really look forward to news in this thread. There is nothing like getting experience with someone else doing all the hard work :-). Thanks for your perseverance Robert.

        • Robert Calk

          May 21, 2015 at 10:05 pm

          Hi Frank. Yes that's true, but it's more fun doing the experiments ourselves.

  14. yaghob

    May 20, 2015 at 8:11 pm

    very very thanks

    • Robert Calk

      May 20, 2015 at 11:18 pm

      Thanks Yaghob, but I'm still a student.

  15. sam montero

    May 20, 2015 at 8:44 pm

    Hi Robert
    Its frustrating but I think you still have fun playing
    with this IC. I believe the ICs are really rejects
    which are sold by third party suppliers. In my
    experience while working on semiconductor
    company, rejects are sold as scrap for toy
    application or to recycle the gold in it. These
    ICs are marked before testing so rejecs are still
    marked. mostly buyers are from Hongkong.

    • Robert Calk

      May 20, 2015 at 11:22 pm

      Thanks Sam. Yes it is fun learning and experimenting. It's also fun sharing it and getting ideas from you guys. You may be right about the IC's. I will try Andre's supplier and see if they have this IC.

  16. reza

    May 21, 2015 at 2:31 pm

    hi dear Robert Calk
    thank u for sharing this article.
    u have beautiful workshop
    m.reza from iran

    • Robert Calk

      May 21, 2015 at 10:07 pm

      Thanks Riza. I'm glad you enjoyed the article.

  17. Taring K Arioka

    May 22, 2015 at 6:05 pm

    Hi Robert Calk

    Thank you for this article. I learned one important lesson from it which is test every part before considering them as useless pieces.

    • Robert Calk

      May 22, 2015 at 9:32 pm

      Hi Taring,
      You are very welcome! From now on I'll test the IC's on the PCB they were originally on, if possible. But I had already stripped the router board of the components when I got bored one day, then decided to test the IC.

  18. Humberto

    May 23, 2015 at 1:33 am

    Great article Robert, you have been persistent looking for the culprit. Congratulations.

    • Robert Calk

      May 25, 2015 at 8:27 am

      Thanks Humberto.


    May 24, 2015 at 12:12 pm

    Dear Robert,
    very nice article. i'm also interested in troubleshooting too. i used to order from them too but so far so goood except i order the recycle components.
    As my experience, this IC can stand the ESD and protect from damage without ESD bag, only killed by soldering without ground.
    To my point of view, maybe i make a mistake, the IC pin 3 is suppose connect directly to 10uH & 10nf . the 26.1K is connect to other side of the 10uH & 3.3Vout . maybe this make the output fail and IC burnt out of control. cannot detect the EMF of the 10uH.
    Based on your breadboard wiring, the 10uH is wired liked C8,high EMF switch by pin3 ,which induced directly to FB pin 5, this will killed the IC instantly or when you raise up the voltage.
    thanks , this is just my observation.

    • Robert Calk

      May 25, 2015 at 8:48 am

      That may be the problem. I only raised the voltage on a couple of the IC's, so I'll change the circuit and check them out. Thanks.

  20. David

    May 24, 2015 at 12:45 pm

    Seriously folks!?!?...has no one heard of a IC holder. You solder that into the circuit and plug your IC into that...just clean the pins if they don't look new. I'm almost sure you busted your IC soldering them in. I have ordered and replaced many ICs without static gear and they still are working.

    • Robert Calk

      May 25, 2015 at 8:50 am

      Thanks. I've soldered many IC's without ruining them. My soldering is not the problem.


      May 25, 2015 at 12:03 pm

      Seriously folks ???!!!!!heard about Ice Cube holder ???!!!
      just kidding.
      don't under tension ..... this is electronic world ,we are just playing with SMD IC.the point is fun, don't miss out this fact,please !!!
      we like to make an alien web like wiring/circuit , that's it !
      ROBERT is our fun GURU.

    • Robert Calk

      May 30, 2015 at 3:45 pm

      Hi David. As it turns out Steven was right! I'm working on the article now, and I'm getting nearly 3.2V at 320KHz on the first IC that I pulled out of the bag after fixing the breadboard as Steven suggested. I'm surprised that I didn't notice my mistake, but no one is perfect.
      I should be sending the article to Mr. Yong in a day or two.
      Thanks guys - I appreciate the comments and suggestions.
      Oh, also in Playing with IC's Part 3, I will be revealing a secret that few people know about! I don't remember ever reading about it in any electronics books. So don't miss it!

      • STEVEN NEO

        June 1, 2015 at 4:49 pm

        Hi ... Robert. nice to hear that finally you had succeed.
        making mistake is just part of the life but we will learnt a lesson.
        cause i always make this type of mistake and kill the components and will careful before change the parts. will check through pin to pin and component to component.
        BONUS ... can help other to solve it!
        you are welcome .. ROBERT.

  21. jun

    July 7, 2015 at 10:50 am

    I'm very much happy upon reading this article, Hopefully can get more knowledge about electronics. thanks robert

    • Robert Calk

      July 11, 2015 at 1:56 am

      Hi Jun. I am happy that you enjoyed it. Be sure to read the Part 3 article!


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