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A Hidden Threat To Handhelds
Logic Bomb writes: "An article from the San Francisco Chronicle focuses on a lawsuit against Palm, but talks about a larger issue: static and handheld computers. Basically, as computing equipment becomes smaller and more likely to be carried around, major damage from static becomes a serious threat. As the blurb at the end of the article says, it takes 3500 volts for a human to feel a shock, but only 200 to potentially scramble a microchip." We already mentioned the lawsuit, but this has more information about the supposed risks to your motherboard.
..of blatant negligence on Palm's part, or a case of corporate stupidity, or a little of both?
If they prove that Palm knowingly sent out these devices knowing they could toast h/w, then unleash the hounds...but if it was a simple oversight (which is highly unlikely), well thats where things get interesting....
personally, i think we're getting a little too sue happy these days...
I lost my concept of community when my community lost all concept of me.
Basically, as computing
;-p~
equipment becomes smaller and more likely to be
carried around, major damage from static becomes a
serious threat.
So don't stay static and yer safe! Keep on moving boy
~~~Please pass the salt, I hate unsalted MD5s
It doesn't matter how small it is. Since It's a Class B computing device it can only radiate a certain amount of emissions (or is that just RF). The user should simply be aware that any electronic device will carry this risk, no matter how small, and by purchasing the device, assumes the risk... No harm no foul...
A bunch of lawyers just decided that they might be able to make a quick buck here...
--CTH
--Got Lists? | Top 95 Star Wars Line
It must have been my imagination that hurt when I plugged that paperclip into the wall outlet.
it takes 3500 volts for a human to feel a shock, but only 200 to potentially scramble a microchip.
excuse me? it depends on the current flowing and stuff.. for example, I got shocked by 240v two days ago, and i bloody well fealt it.
stuff
"As the blurb at the end of the article says, it takes 3500 volts for a human to feel a shock, but only 200 to potentially scramble a microchip."
You can say the same thing about water - it takes quite a few drops for humans to notice that it's raining, but just one well-placed droplet will fry your motherboard. Do you see me suing Toshiba because I can't use my laptop by the pool?
What's your damage, Heather?
He said that damage attributable to static electricity causes losses to the global electronics industry in excess of $45 billion per year. The estimate, based on a sampling of electronics companies, includes the cost of damaged goods and their replacement, and field service for equipment repair.
;)
I wonder if the Damage by static is the default option in the returns database of these manufacturers
Partly wrong....you can become an electrical conductor at any voltage if the conditions are right. Besides, it takes a combination of the right voltage pushing a high enough current to hurt or kill you. 100mA conducted through the body is enough current to kill the average person. When you get zapped by static electricity, there is a potential there of about 13kV....but there is a very small amount of current....that is way you don't get hurt.
"No Comm, No Bomb"
--CTH
--Got Lists? | Top 95 Star Wars Line
All they'll have to do is have a grounding connector pin placed slightly ahead of the data and power pins on the connector. Hot swap drives do this today, why can't handhelds?
-- Minds are like parachutes... they work best when open.
It doesn't take 3500 volts for a human to feel a shock, naturally. It takes 3500 volts for a human to feel a static discharge, which is what the story asserted.
www.timcoleman.com is a total waste of your time. Never go there.
Ever tried one of them 9v things on your tongue? I did, plenty, when I was a kid, not quite painfull but you feel it.
Somehow I also managed to get my tongue stuck on my toy racing track once (which was like 12 or 18v or so).
THAT HURT!
-- Si hoc legere scis nimium eruditionis habes.
So, I wonder how this could potentially play with Docker's new pants. You know the ones that I'm talking about. They have the extra hidden pockets.
Instead of keeping your Palm in a proper case, you carry it around in fabric where it can move around and possibly create some static and then you go to unzip and grab it and you don't even feel the zap, but then the Palm won't turn on.
And those x-ray glasses in the ad really fool ya too.
The article mentions that it could destroy the serial port of your computer? So what, just replace the serial I/O card and it works again! (hmmm... these days the serial ports are on the motherboard). Unplugged your printer one too many times? Replace the printercard (euh... these days the parrallel ports are on the motherboard). Videocards? On the motherboard. USB ports? On the motherboard. IDE/FDDI cards? on the motherboard. Ethernetcards? On the motherboard. Sounddevices? On the motherboard.
Why is everything so all integrated into one device? Why is there a chance the videocard gets broken when something happens to my serial port?
bash$
Stephen Wise, a San Francisco accountant, said he smelled smoke and heard a crackle of static after putting his Palm Vx in the cradle. Wise claims his computer was damaged, forcing him to replace his PC during the busy tax season.
Great example to give... certain to frighten every non-tech out there. Of course, how many times have you 'smelled smoke' from an ESD? Sheesh.
'Life is like a spoonful of Drain-O, it feels good on the way down but leaves you feeling hollow inside'
A human can be given a shock/electricuted at even 12V given enough current.
I believe that the poster is unfamiliar with today's microelectronics. Yes, static electricity has gotten a bigger deal as the geometries have gotten smaller. However, do you remember the days of the PC clones with static strips nearby? If you didn't touch the static strip and were walking on carpet, you could fry the entire computer (my friend toasted two motherboards that way, by way of the keyboard). How often do you hear about this kind of thing today? (Expected answer: every now and then) How does this compare to the days that electronics were much less pervasive? (Expected answer: It happens less often)
The reason behind this is that chip manufacturers have been working on modelling the kinds of static electricity that humans produce (human body models) and machines produce (machine models), and designing I/Os to accomodate the new parameters.
Yes, some companies take their chances, ignoring static electricity (and there are some performance benefits to doing that), but these are risks that most of us can weigh.
For example, a 2-year-old whose hands wander onto the family computer could accidentally cause a static discharge -- and the equipment must be designed to withstand it, said hardware engineer Stephen Smith of Luxon, a Bay Area firm that makes graphics for portable devices.
Of cause it should be able to withstand some amount of static, but how much is the limit before you risk a lawsuit? If we create an environment with the right combination of carpets and shoos; I believe we could kill any device. Should the manufacture then put a lawsuit against us?
What about shock absorption? Should we put up a lawsuit, just because we dropped our palm on the floor? I think its common sense that things being dropped on the floor break... but I also thing it's obvious that high levels of static's will destroy electronics. If I produce hardware is I then responsible of educating people? What about water and electronics? Should I tell people not to plug the palm into the power sockets? Etc...
I know it is difficult to put up the line between a bad piece of hardware and a bad use, but it appears that everything goes into lawsuits rather than trying to counteract the actual problem. Hardware may be damaged if it is badly produced and/or is misused.
-:) Oh no - not again.
www.rednebula.com
I doubt that this is the case at all. It would be very difficult to get a charge to travel in one of the serial ports wires and not get grounded on the way there. Furthermore, the serial port, being one of the available external ports, is generally very well protected from static discharge. The real problem here is that nearly every integrated mobo has the serial port contained in the northbridge/southbridge chipset, so discharge to the port means discharge to a critical IC in the computer as well.
Good mobos will have protection right at the port, including zener diodes and possibly MOVs (MOVs break down and conduct at high voltages, zeners prevent the voltage going above a certain point, in this case above or below 13 volts or so).
The actual IC will generally also contain similar protection.
But this isn't an issue of whether it happened, or is even a remote problem. This is the "The coffee burnt my lap" problem. In our increasingly litigious society we sue people for not warning us of possible problems. All computer and electronic devices say "Static electricity may cause damage to device." What these laywers apparently want is Palm to put in big bold letters that "This device may act as an additional path for static electricity to damage your computer or other palm attached device." Which is silly. The user, had they read their documentation, knows that both devices are sensitive to static. Do they think they are immune to it by ganging the devices up?
Another lowest common denominator problem...
-Adam
A handheld is much more likely to get stolen by a savage nigger or broken by a drunken spic than getting destroyed by static electricity.
And the amperage also has an effect.
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Serial ports (I'll stick with RS-232 and 485 - I'm most familiar with them) use voltage & logic shifters to handle the conversion of the port voltages to internal logic voltages. For years, most RS_232 ports on PCs used the MC148x or MAX232 type serial inetrface chips - got news for you, NONE of these chips have ESD hardening. RS-485 ports were even worse - they used a chip called a 75176 - those things would blow when you pulled one out of a pack to insert it in place of a blown chip. Ever notice how many cards with 1489type interface ICs had them in sockets? There was a reason - I've replaced a fw in mine.
I've designed embedded boards for Home automation and our boards used RS_485 which gives you long distance (1000-4000') over twisted pair at decent speeds for system control. The original design (which I didn't do and which was done BEFORE ESD variant chips were available) used the 75176. I had customers calling for replacements all the time. Those long twisted pair cables connecting nodes together were asking to induce surges AND when folks wired them up with bare hands and no static strap - they induced charges into the wires connected to all other nodes!
Maxim IC came to the rescue by developing the MAX232E and MAX485E which were ESD hardened interface ICs for RS-232 and 485 respectively. These things are amazing. One article I read had a guy sending massive (like 40kV) pulses into these chips and they survived. They are rated for +15kv and man do they work. When we switched to these chips (our main controller had both RS_232 and RS-485) our serial bus failures went away. TO dtae I have not had a customer complain about a failed ESD hardened chip from Maxim. Only problem is they ARE more expensive - about double. But WELL worth it IMHO.
Obviously - anyone handling motherboards or any other bare electronic board without using a static strp is an idiot - you're just ASKING for it - and um if you unplug your PC and then ground your strap to the case - it doesn't help much sinc ethe case is only grounded when its plugged in! You have ot ground your strap to somethign thats grounded!
But ddesigning your system with external ports and not using ESD haardened ICs and surge supressing devices is just asking for trouble - but these things cost money. Surge problems are worse than ESD often. But the savings in customer satisfaction and warranty repair costs often outweigh the extra pennies - but its hard to measure.
As for static straps - its amazing how people hate them so. I managed a 10k sq ft data center with almost 700 servers, from small $5000 machines to monster Auspex boxes costing millions. We implemented a policy that every tech in teh room had to wear a static strap on theri wrist, shoe, or static shoes and had to test the device when they entered (testers at every door) This was for ISo compliance but it was also smart. A single board for an Auspex might cost $50,000 to $250,000!!!! Yet I constantly had to police the situation and hassle people because they refused to wear the straps. The worst were the Sysadmins - they figured since they didn't touch teh cards themselves it was OK, yet they were plugging serial cables into exposed serial ports to hook up root terminals (before we had a networked root term setup) It was amazing the resistance I encountered for such a simple thing.
The bottom line is, if you are design a device for end use - spend the $$$ on ESD and surge suppression. If you are a tech or even a hobbiest working on teh guts of a PC or even hooking UP a PC that might not have said ESD protection, wear the strap or shoes. All it takes is one zap and thousands of dollars go up in a spark!
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Instead of soldering the chip to the motherboard, just fasten it with a piece of play-doh. Or better yet, an eraser - they're made of rubber so the static electricity can't pass through them - problem solved!
My Karma was at 49, then they switched to words. All that work for nothing!
It's unbelievable... There's no doubt that both palm and Motherboard Manufacturers should do better when designing for ESD resistance, but users should be careful rather than sue... but this, I guess is the american way...
--CTH
--Got Lists? | Top 95 Star Wars Line
Can I sue the makers of poly-propylene for toasting my palm? I get zapped non-stop while wearing this stuff.
IIRC from my early Computer Engineering classes, all it takes to damage a circuit is +5 volts or static electricity. It seems like it was something around +10,000 volts of static electricity before we as humans feel it. I think that's right. I'll have to dig out my old books. They showed a demonstration video of a typical engineer in a simple short sleeved button down shirt (plain) and simple tie. He neutralized himself (voltage equalization IIRC). Then someone (also equalized) held the tie at shoulder level just away from the 1st guy's shirt. He let go and let the tie brush against the guy's shirt. They then measured how much static electtricity was generated. It was more than enough to damage a circuit board. Mind you, +5v probably won't toast a board right away but it could easily cause damage that shows up down the road. IIRC correctly of course. It's been a while since I had that class.
From the article: "You cannot expect people to become more educated," Smith said. "The equipment has to be perfectly safe."
See, here's why there are so many lawsuits and bad stuff (like the DMCA... do I get extra karma points for mentioning the DMCA in a completely unrelated discussion? Ah well, nevermind) happens.
Expectations. If you don't expect people to be educated, then they never will be. Instead of having so many lawyers going "my poor client didn't knew thay you shouldn't stand at the top of a 15-foot metal ladder in the middle of a thunderstorm, while installing his TV antenna", you should get more judges who think "Serves you right for being such an idiot. Next case!".
I agree that sometimes consumers must be protected from Evil Corporations Who Want To Take Over The World, but there's a big difference between: a) not letting oneself get screwed by the Evil Corporations etc.; and b) blaming the Evil Corporations etc. for each and every stupid accident that could have been prevented with a little common sense.
As usual, let's blame the lawyers instead.
Tongue-tied and twisted, just an earth-bound misfit, I
Learning to fly, Pink Floyd.
Sticka 9V battery to your tounge. Other things well under 3500 that I've been shocked by: telephone not ringing ~50v, telephone ringing ~200v i think (not a social sock, an electrical one =) the mains, and finally and electric fence.
There's no doubt that both palm and Motherboard Manufacturers should do better when designing for ESD resistance.
Sure, they could ESD harden the motherboards, but are you willing to pay for the increase in cost?
Basically Mr. Sue-Happy is gonna raise the price of your computer components. I'd rather have cheaper components than pay for someone elses uneducated electronics bumblings.
Perhaps the reason you managed that is that your family name is Binks?
It's not about AC vs. DC at all. The article is referring to static discharge, which is the equilization of differing voltage levels. Here's the google cache of the first decent explanation I dug up on google. I'm sure you can find more yourself.
https://www.eff.org/https-everywhere
Yes and no. It takes about 0.183A (IIRC) to cause your heart to go into an irregular pattern, resulting in a heart attack. Higher current loads through the heart are different; They cause it to stop, and (likely) start beating again. This is the principle used to start your heart again after it's stopped beating.
Much has to do with the resistance in ohms of your skin when you have the electrical shock applied; Are you doing something stupid like working on a grounded metal roof in wet bare feet with power tools (case study in class, that one), etc etc etc.
Many variables are at play here; Power is dangerous and something to be resepected at any level. I zapped myself real good with 25kV once, never again .. :)
..don't panic
Have you shocked yourself on a speaker? A Mouse? A Keyboard? Each of those devices can roast the computer it's attached too. I don't remember seeing people run around sueing the manufacturers of those devices. The same 'ground yerself before you touch' principle holds up for any device attached to a computer.
As a rock-in-roll Physicist once said, No matter where you go, there you are.
3 months into my new Visor, I had one final hard reset incident, and after that my USB port became non-functional (I also have a USB Zip drive that I use several times a day, so I can tell you precisely when it died). Hardware support happily arrived and replaced the system board in my Dell, but I was wondering what could possibly by the problem that caused the failure in the first place?
Eventually, I exchanged the Visor, and brought the new one back to work. I put it in the sync cradle. *reboot*.
At this point, I knew it wasnt the Visor, and I knew it wasnt the Dell, but it was obviously some combination of the two. As an experiment, I went a week with a grounded anti-static wriststrap wrapped around the back of the sync cradle. I made a point of touching it before I set the Visor in the cradle. Lo and behold, no more hard resets!
I decided to make this modification more or less permanent. I found the ground cable in the cradle, and the corresponding copper spring clip where it mates to the Visor. Using a trusty set of hemostats, I bent and extended it up to where it is the first bit of the cradle that touches the Visor. On the other end of the sync cable, I ran a little pigtail wire from the metal sheath of the male USB port to a screw on the back of the case.
This has the benefit of directing any static directly to the ground of the case, instead of routing the discharge through the USB controller, to *it's* ground.
Now, I dont really know whether or not this worked, because static shocks are pretty rare here in the summer (St. Louis, MO, where the humidity rarely drops beloe 75%). I'll have to wait until this winter, when the central heat kicks in, and the relative humidity in the office is about 15% before we see whether or not I've improved my sync cradle.
This space for rent.
"it takes 3500 volts for a human to feel a shock, but only 200 to potentially scramble a microchip"
.000005 amps and you will never notice, but one hundred volts at five amps will light your ass up!
When will the world catch on that it is not the volts that matter, but the amps! I can hit you with a million volts at
The article only mentions cradles attached to a serial port. Does this affect cradles attached to a USB port as well?
Anybody who uses a computer without knowing how it works deserves whatever evil befalls him.
******
"What makes you think I care about your opinions?"
The "reasonable person" was taught in my paralegal classes as last as last semester--and it doesn't seem to be getting loose.
In addiontal to "common sense", a reasonable man never comits a tort, nor does he ever fail to read everything he agrees to, nor the instruciton manual of anything he gets.
A simple "warning, these are very succeptible to static electricty" would probably suffice for the PDAs, but then again, IANAL.
It's rather silly that the plastic plates are not available separately. But I guess they have calculated that they make more money selling entire new screens or even new PDAs...
I'd call that level of repairability as useless. People really should pay more attention to this kind of problems.
Think "programmer with screwdriver" or "phd with soldering iron". Common sense and intelligence often seem to be inversely proportional.
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Things are more complex than just the amount of voltage you get through your body. One can die from 400V and survive from a shock of 10000V. How come? The current is very important and so is how well you are grounded.
(The funny thing is, the 220V (110V US) we use daily is less dangerous than the 24V in your phone when ringing.)
How much current is dangerous? Well, 5 milliamperes can be felt, 10 will be felt and hurts, 15 will really hurt, 30 will freeze you on to the current source. And we are just talking about milliamperes people.
42 + 1 = 42
Why is everything so all integrated into one device?
The last integrated motherboard I bought cost less than the last separate serial card I bought.
>Much has to do with the resistance in ohms of your skin when you have the electrical shock applied;
>It takes about 0.183A (IIRC) to cause your heart to go into an irregular pattern, resulting in a heart attack.
Interesting. So does this mean that if you loaded a watch battery (milliAh = up to 500) into a 38 shell and shot someone (in the right place I guess) they'd have a heart attack? If so why do tasers have wires?
The sheer number of people who do not understand this principle baffles me.
Volts mean nothing when it comes to whether or not you will feel a shock.. its the amps! the amps!
The most irritating thing is that already, several posts down, someone has already posted without a clear understanding of this concept. To paraphrase: I've been shocked by a 9v battery, so i don't know what they are talking about feeling 3500V when I.. ug.
Moderators: please mod the parent post up. Maybe then at least a few people will get a clue.
Get your hands off me you damn, dirty amps! - sorry, couldn't resist.
// harborpirate
// Slashbots off the starboard bow!
All that would have been required to insulate the PC from the handheld device is a simple little ferrite bead. (Read iron donut) around the wires. The ESD shock travels up both wires simultaneously, and by using the bead, it is all but rejected. This is quite common and you can see it if you look at monitor cables. In fact, I believe that my digital camera has a similar device on its serial interface cable.
Does this only effect Palms? I'd like to know if I need to worry about frying my Revo. At least they are all small enough to carry around in anti-static bags if needed....
Jaysyn
There is a war going on for your mind.
Talk about frivolous lawsuits. I mean, what's next? I'm suing E-bay because I couldn't type my bid fast enough before the deadline?
I, for one, have put my Palm III/e through hell and back. I'm a high school student, and my Palm has been dropped, scratched (yes, the screen), beaten, bruised, and has even been on a trip through the washing machine along with my pager. Guess which one survived? I'm just saying that from my experience, Palm makes some hearty PDAs.
--Goat
CEO, Goat Software
Goatblog
Hmm, my double E classes always insisted it was much lower like 30 volts of static. The A+ exams said the same.
Mod point free since 2001
I have ruined memory sticks, cache on motherboards and who knows what else due to static charges, but you don't see me running to a lawyer crying "mommy, mommy, the bad man MADE me do it! waaaaaaahhhh!!!"
This just looks like another case of someone trying to get rich off their ignorance of technology.
A vacuum is a hell of a lot better than some of the stuff that nature replaces it with. - Tennessee Williams
If you're running ANY electronics in an environment like that, you'll see it die, eventually, if not sooner. It doesn't matter what you connect, once you put a wire outside of the computer, it's another route for things to get zapped.
--Mike--
Power = Current times voltage. Current is charge over time. Almost zero charge at any voltage is almost no power.
If a single electron hits you at a couple million volts, you won't feel it. Charge doesn't come in volts, it comes in farads.
This whole thing about static is an excuse for bad quality construction. Static shocks haven't blown out chips since since the early 1970s when CMOS B was invented. Crooks like 3M use people's fears and ignorance to sell anti-static this and that. Any surprise that lawyers would pick up the racket?
It is easier for companies to use "anti-static bags" and other talsmans for the easily scared than to teach simple physics to the masses. But I'd expect better from those seeking "News for Nerds."
All those physics formulas you had to learn in your first electronics class apply in the real world too, not just way back in school.
Any computer that can't handle a static discharge to any external port, especially a serial port, is defective. Any lawsuits should be directed to the computer maker (or /dev/null).
------DO NOT WRITE BELOW THIS LINE------
Without some ESD protection, every integrated circuit would be damaged by ESD during the manufacturing, test or assembly process. Typical standards for ICs require that a device withstand a zap of 2000 volts through a single data pin the power or ground planes of a device (aka "human body model"). Zaps applied to a power/ground pin on one power plane must also not damage anything.
There are special protections circuits used to achieve this. In the past, a simple back-to-back diode arrangement from the data pin to power and ground was sufficient. But specialty input/output types and mixed voltages (think of 3.3V PCI I/O on a 5V PCI system, which is part of the PCI spec, or a hot-plug SCSI bus) changed all that. The 2000 volt spec has not changed, however. So semiconductor manufacturers must be very diligent and test the heck out of their devices to be sure they are production-worthy.
As a note, one chip that a previous company I worked for had built had a major ESD issue and could be damaged by a 200 volt zap. They had to institute very, very special handling procedures to avoid damaging devices during testing. 200 volts happens *very* easily in testing -- the old tubes used to hold DIP parts could allow a device to build up that kind of charge while sliding them into a metal chip handler for testing. Yes, even anti-static tubes and bags only afford protection to a certain level.
As for the Palm cradles, it's difficult to say how to control an ESD zap from getting to the mobo in some way or another; the charge has to go somewhere and the cradle isn't grounded so that's not an option for a discharge path. But SCSI drives such as SCA in a hot-plug environment must deal with potentially zapping the backplane (and hence the motherboard), so I assume there are ways to mitigate this at the system level as well.
- Leo
You don't use science to show that you're right, you use science to become right.
Let's see now 13 million PDAs, the lawyers say they estimate there are, hundreds of thousands devices, that's like a
If someone is passing you on the right, you are an asshole for driving in the wrong lane.
Funny how some old problems keep coming back to haunt in in microelectronics. During the '80s, the static discharge problem was a big, bad, recognized problems. I remember cringing at the area "wasted" by ESD diods protecting the I/Os of 4-bit microcontrollers. (What do you mean, I am old? Beware of my cane, young fool!)
Then ESD prevention became part of the run-of-the-mill process, and not much attention was paid to it anymore. From time to time, though, a grim-faced test engineer showed up with a microphotography of a (relatively) huge hole in a faulty chip analyzed for default characterization, and asked for some extra grounding to be added on a new wafer manipulation station. But that was about it.
Now the problem is back again. What happened?! Well, the ESD absorbtion device don't shrink very well. So smaller chips with huge I/O counts mean that the chip real estate occupied by ESD prevention is a major nuisance now, and then there is the issue of the ever-decreasing geometry size while the static voltage are remaining constant.
So Moore's law makes the problem worse, not better. Now add the packaging of consumer device, which is increasingly shoddy (whatever happened to metal shields inside consumer devices?). Maybe someday we'll have to be as cautious around our consumer electronics as we once were around a memory expansion board.
#include <memories.h>: Once I was working in a customer's building where a programming lab had been hastily installed. A synthetic carpet had been laid over the old hardwood floor. The old heaters were dessicating the air so much our lips hurt. Enter a young, skinny woman wearing three layers of acrylic sweaters, as well as hose and plastic-sole sneakers. She reached down to insert a diskette into the Unix server. We all heard an audible crack when a 10-inch long spark jumped from her hand to the keyswitch. She yelped. We moaned: the server has crashed. Postmortem revealed that the processor detected an ECC failure during memory access. So the massive ESD had scrambled the bus. But it restarted OK.
Ground-strap these skinny girls during the winter!
--SysKoll
--
Mad science! Robots! Underwear! Cute girls! Full comic online! http://www.girlgeniusonline.com/
Lacking <sarcasm> tags,
$5 for peace-of-mind? Sounds like a good trade to me.
Hardware, software, and blinking lights!
...where do you buy yours?
Static discharges can destroy many an integrated circuit if there is improper internal protection. Think about it, if one external pin of a device is connected to the gate of one MOSFET (which can happen sometimes), and that pin suddenly accumulates charge through ESD, it won't take much for the oxide to break down between the gate and the substrate, and then you've got a chip that won't work.
Say the ESD pulse happened on the power (or gnd) line. Suddenly, across your entire chip, you have a 200V difference between power and gnd for a fraction of a second. Unless you've specifically added extra circuitry to cope with this (and any knowledgable designer will), something's gonna blow, even if it is for just a fraction of a second. With a 200V potential difference, it doesn't take long for 77 angstroms of SiO2 to break down.
Standard ESD protection within a chip consists of control circuitry that will turn on a low-resistance path between any two pins whenever the potential difference becomes too great. The plan is to make the current flow through a large internal ESD bus, rather than through the delicate core circuitry of your device.
Of course, a good defense is to prevent static discharges from ever reaching your device. Anti-static bags provide a conductive path around the outside of the bag, so that the least resistive path is not through your device, but rather around the outside of the bag. They are in general a very good idea, because there is no telling what kind of ESDs you can encounter during shipping and handling, whereas when a component has been installed somewhere, the ESD that it will encounter can generally be predicted.
PS - Charge is measured in Coulombs, capacitance is measured in Farads.
It may look like I'm doing nothing, but I'm actively waiting for my problems to go away.
--Scott Adams
The San Francisco Chronicle wrote, Static electricity can discharge more easily through dry, cold air than in humid weather.
This is incorrect. We experience shocks when the air is dry because humid air prevents the static charges from building up in the first place.
An AC source, however, you're acting as an antenna. Any amount of current you radiate into the air causes current to flow through you, hence the shock. At 60Hz, you're only getting a little wussy shock, it would have been a LOT worse if you'd grounded back into the other end of the socket.
At higher frequencies (think Tesla coils) you actually can radiate most of the current, although at the higher end, the "skin" effect will protect you to some degree (hence Tesla used to stand on insulating platforms, touching a live coil with one hand and fire lightning from his fingers ;)
Hardware, software, and blinking lights!
Palm could simply supply an ESD protection 'dongle' for the PC's serial port with the Palm; it's surely the kind of thing that Radio Shack supplies for <~ USD 10.
Thirty years ago I worked for Digital Equipment Corp, as a systems testing engineer. Our department did hardware and software testing of all systems configurations that went out the door, I worked on the LSI-11 based stuff. One of the tests we had to do was for ESD, or static discharge as it was there called. The test consited of drawing an arc from any exposed surface of the equipment, to pass it had to withstand an arc of at least 5000 volts (IIRC). The tester was a high voltage power supply that could be adjusted to as high as 15kv (it was limited to a few MA). The probe was an old VTVM high voltage probe with the tip replaced by a metal sphere about 6-8" in diameter. The tester would crank up the voltage and pass the sphere around the outside of the computer to draw an arc from various locations as the computer was running a systems diagnostic. There had to be no systems failures. Usually we didn't fry anything (I can't remember ever destroying anything), but sometimes the diagnostic would fault or the computer would re-boot when the arc was drawn. I wonder if any of todays PC's could pass such a test? (Not running windows!, probably get the BSOD when you draw an arc!).
Lawyers are just getting bored if you ask me.
Of course, it drops below 20K when I have wet, SALTY hands (stupid potato chips). Then again, that's about the worst combination you can achieve.
Hardware, software, and blinking lights!
Furthermore, The 1970's were almost entirely dominated by TTL logic, which is almost immune to static (you can still kill it, but you need to be TRYING). In the case of TTL, current is what kills it.
Thing is, CMOS doesn't work like that. A MOS transistor has a thin layer of metal oxide which acts as a capacitor. When the voltage across it exceeds the dielectric ability to withstand voltage (I forget the term....), then it pops, and, just like that, it's ruined. Voltage is the killer for CMOS, which is why ESD has become an issue.
Hardware, software, and blinking lights!
jerking off while browsing at -1... mmm mmm mmm...
I have been trying to post articles on Slashdot for a month now, but they are insistant on publishing other articles. I just posted an article on Quantum Computing. I think you will all enjoy it quite a bit. For those of you who do not know what Quantum computing is, the article explains it quite well. Here is the link . You can post comments on the article below it. Please tell me what you think.
I've played with these devices. X86 compatible even (and MUCH more expensive than the average Palm, they ran about $5000 for the 8088 model). The heavy plastic and rubberized corners were truly a sight to behold.
Personally, I'd want my handheld to be able to handle a drop of at least 4 feet to cement (since that's the normal operating height) without breaking, since handhelds DO get dropped ocassionally (my current handheld is a TI-89 *wink*, which is actually pretty rugged).
Hardware, software, and blinking lights!
...damage attributable to static electricity causes losses to the global electronics industry in excess of $45 billion per year...
Would that include lightning strikes? (If I remember gradeschool science correctly, lightning is static electricity on a big scale...)
$45 billion dollars? that sounds kind of high - Any chance Bill Gates will off himself scuffing across the carpet in his slippers next year?
Cheers,
Jim in Tokyo
-- My Weblog.
"You cannot expect people to become more educated," Smith said. "The equipment has to be perfectly safe."
so are cars supposed to be perfectly safe? dont we have education classes to safely operate one? we have speed limits, but cars still operate at 120 mph +
Once we get past the Streetfighter-esque title, we need to realize that static electricity is much more mysterious than most people think. When you remember that everything that occurs in everyday life has electrons, its easy to see where you can pick up spare electrons from objects. Also, the charge in your left leg might be much more or less than your hand. So it really is possible to collect a really large static charge, and discharge it (electrons seem to pull each other like water pouring or something). This, and a combination of cheap electronics, leads to some pissed-off users. Static electricity is a fact of life. I agree hotsyncing a palm shouldn't 0wn your computer/ports or anything like that, but if you decide to leave your computer on 24/7 with the cradle plugged in, something is BOUND to happen after a while. Taking into consideration a shitty motherboard, shoddy cradle, and negative karma, the motherboard or cradle can take just enough damage to make something happen when a major electrical change occurs.
Job? I don't have time to get a job! Who will sit around and bitch about being broke and unemployed then?
And how do you propose to get exactly 100 volts and 5 amps into me if I resist?
I do electrostatic discharge and interference tests for a living. We can produce electrostatic discharges ranging from a few hundred volts to over 300 thousand volts (landing aircraft) in house. We also radiate products with radio frequency interference from a few hundred kilohertz up to the microwave range. Sometimes we just listen to what products put out as well.
Most of the devices we test are safety-critical. Your home computer likely will never be seen in our lab. We recently conducted a test where a product in its box was shocked with a 300 kV static discharge. The spark (besides traveling three feet) went through the box, in one terminal of the item, and out another.
While charges on your body are not nearly that strong (the highest you'll build up likely is 25-30 kV), you shouldn't laugh at them.
Many modern manufactuers no longer include safety components ment for repair technicians. Often saving less than a fraction of a cent (in bulk), the lack of these parts make it an extreme risk to open things like microwaves and televisions. Not to be dismal, but don't open these items unless you know what you are doing; I have heard of experienced technicians putting their hand in the wrong place and regretting it.
Quick and simple.
On another topic: Your comment violated the postercomment compression filter. Comment aborted
Lose the lameness filter, Taco.
Yes, believe it or not, modern computers are quite sturdy. I've beveled the edges of my Duron with homebrew watercooling tech., I've passed current through my heatsink (melting the contact points to boot), hooked up who knows what to the serial ports, and currently my tv card is being fed via telephone wire because I ran out of coax. On top of that, I unplugged and then plugged back in my cdrom drive while my computer was running, producing a bright arc of electricity and a seemingly dead motherboard, which I revived the next day. These people are either unlucky that their computer fried, bought cheap crap, or they want cash (probably the latter).
The best way to accelerate a windows box is at 9.8 meters per second square.
Quick and simple
...the older IBM 'clacking' keyboards, pre windows key, etc. I've been shocked removing a 5.25" disk from a floppy drive when I touched the disk, and the casing on those is plastic.
(yes, I meant 5.25")
As a rock-in-roll Physicist once said, No matter where you go, there you are.