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Accidently applied 6V on the Propeller! — Parallax Forums

Accidently applied 6V on the Propeller!

John A. ZoidbergJohn A. Zoidberg Posts: 514
edited 2010-10-22 08:00 in Propeller 1
Hey guys,

I was doing some stuff on the Propeller, when I accidently connected the Vdd into the 9V battery directly for a short moment.

The thing is, it gets just what I feels warm (a very faint) on the chip, and then I pulled out the supply immediately. My 9V battery measures 6~7V prior to connecting because I had used it up a little bit.

I think I may have burnt it, but when I tested the chip, it worked okay.

Should I further test the chip? I do not know how to check for further damages done in the chip. Thanks.:lol:

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-10-21 20:33
    There is no "test" for damage to the chip. The chip is rated for no more than 4.3V (I think that's right) to be applied between any two pins including Vdd and Vss. The chip is simply not built to withstand higher voltage. There may be parts that you've not used that are damaged or there may be some early damage that effectively has prematurely aged the chip and the chip may fail after another 100 hours or 1000 hours of use. Who knows?

    Basically, if you use the chip further and it fails and you go back to Parallax and say "hey, look this is broken" and they ask you if you've "abused" the chip and you honestly answer "yes", then they can say "tough", you've damaged it. Now they won't really say that because you're a good customer, but they'll remind you that it's not built for that kind of abuse and you're lucky it worked at all afterwards.
  • John A. ZoidbergJohn A. Zoidberg Posts: 514
    edited 2010-10-21 20:49
    Mike Green wrote: »
    There is no "test" for damage to the chip. The chip is rated for no more than 4.3V (I think that's right) to be applied between any two pins including Vdd and Vss. The chip is simply not built to withstand higher voltage. There may be parts that you've not used that are damaged or there may be some early damage that effectively has prematurely aged the chip and the chip may fail after another 100 hours or 1000 hours of use. Who knows?

    Basically, if you use the chip further and it fails and you go back to Parallax and say "hey, look this is broken" and they ask you if you've "abused" the chip and you honestly answer "yes", then they can say "tough", you've damaged it. Now they won't really say that because you're a good customer, but they'll remind you that it's not built for that kind of abuse and you're lucky it worked at all afterwards.

    Oh well, there is no insurance either, but now I've 'tagged' and 'labelled' that chip already with a small sticker. If it failed for that reason, I could dispose it easily without disposing the wrong chip. :lol:

    Man, I should double-check the connections... really! :lol:
  • TinkersALotTinkersALot Posts: 535
    edited 2010-10-21 21:02
    Believe it or not, I have put 12Vdc into the BS2 pins. Oddly enough I did not cook the device, and here is how I proved it.

    1. Wire a LED circuit to all outputs and test each of them as an output.

    AND AFTER THAT

    2. Wire a DIP switch to all inputs and test each of them as in input.

    It may still have some damage I guess, but this kind of sanity test could prove it one way or the other.
  • william chanwilliam chan Posts: 1,326
    edited 2010-10-22 02:30
    I once accidentally connected 12v to the Propeller Vdd and Vss pin for almost 1 minute.
    The Propeller chip seems to be still working except that it now runs at half the speed of what it's supposed to be.
    That means if I set it up to run at 80Mhz, it runs at only 40MHz.
    I know this because the sounds it played on the speaker is only half the freq i expected.
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-10-22 03:10
    The first Prop I had suffered a reverse volts, due to a modified PSU (not by me). That Prop still works "OK". The only thing that shows up to lead you to suspect it is that on the Turbulence Demo, the word "Turbulence" near the intro glitches a few times.

    About a year ago, I blasted a Prop with 9 Volts due to picking up the wrong lead, and with a 2 Amp PSu to play with the poor little Prop didn't stand a chance. You say that your battery was not in new condition, this can only be a good thing as it would hold less energy for destruction.
  • John A. ZoidbergJohn A. Zoidberg Posts: 514
    edited 2010-10-22 04:51
    This could be my worst mistake after hot-flashing my old computer's BIOS chip - upside down. The chip went hot, along with the sticker on it and made a loud, audible pop!

    Needless to say, the chip didn't survived. It just underwent thermal destruction. I had to toss it into the garbage can.

    By the way, I haven't assess the damage done on the Propeller yet. The 9V battery had been abused by those current-guzzling 7-segments, but I still had to check the extent of the damage.
  • KaosKiddKaosKidd Posts: 296
    edited 2010-10-22 07:20
    Ok... sounds silly BUT...
    On DEV boards and the such, where there is the high probability of applying the wrong source voltage to the propeller, what kind of "over voltage protection" can one put on the propeller to protect it?
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-10-22 08:00
    It really is awkward to make a perfectly safe environment for studying any micro-controller. Users want to have the flexibility to do things their own way.

    And yet, the two biggest failures are consistently over-voltage and reverse polarity. Parallax seems to have found that providing barrel plugs with a positive center and a negative outside work quite well with the reverse polarity problem without some of the negative problems of other schemes.

    I/O Pins are somewhat protected by diodes and quite robust. And then there are schemes of using chips like the 7404 to protect outputs, opto-isolators to protect inputs, and so on. Each has its own pros and cons.

    At the end of the day, we all have to take responsibility for due diligence when we build a circuit, and I suspect that everyone has learned the hard way to check before acting. Then double check again.

    I suppose the issue is why rush to power up devices that you haven't checked out completely? We all do it and end up with a few damaged processors and other rather expensive devices that we set aside for further abuse or toss into a dust bin as a complete failure.

    About the worse electronic habit I ever developed was to strip wires with my teeth. One day when I was about 14 years old, I found myself impulsively starting to put the end of a live 120VAC power cord into my mouth to strip wire. Fortunately, I stopped before doing so and decided that I needed to develop a better attitude about precision and safety.
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