[ale] OT: Router for sale

[Marvin Dickens]

On Mon, 2003-01-27 at 01:44, Mike Panetta wrote:
> On Sat, 2003-01-25 at 16:14, Marvin Dickens wrote:
> > On Sun, 2003-01-26 at 02:24, Mike Panetta wrote:
> > > That would work except for 2 problems... 
> > > 
> > > 1. The current produced by using a multimeter in "Continuity" mode (its
> > > really a real low ohm setting, with a beep) may very well be enough to
> > > kill the IO lines of todays 3.3V (or lower) processors.
> > 
> > Who made the Multimeter that your using and how many decades old is
> > it...?... No multimeter I use is gonna put out anywhere near the
> > amperage necessary to smoke a chip. Voltage is harmless when amperage is
> > low (Basic physics...). All modern multimeters use extremely low
> > amperage with very long wave forms.
> 
> What do wave forms have to do with anything?  

Long wave forms are indicative of AC power which will kill any CMOS
device even at extremely low amperage.

The output of the
> multimeter should be DC when its in continuity (resistance) mode anyway.
> When a chips IO pin is only spec-ed to accept 3.3V and you apply more
> then that to it, it has a chance to get damaged.  And the current is not
> too limited when your in continuity mode (because its a low resistance
> setting) so that it can actually measure the resistance.  I have no
> empirical evidence as to what it is, but I am sure it could easily be
> measured, and if its over 20mA it has a chance of killing the IO pin.  

Consider the following:

Device		Process	Current	Shrink	Current	Die(shrunk)  Ref
1Gb  DRAM	.16um	 240mA	.16um	 240mA	576mm^2	     [Yoo96]
StrongARM/200/1	.35um 	 550mA	.16um	 275mA	 12mm^2	     [Mon96]
PPC/200/2	.50um	1600mA	.16um	 355mA	  9mm^2      [San96]
DEC Alpha/433/4	.35um  12500mA	.16um   6250mA	 52mm^2	     [Gron96]

The above stats were given in papers by each respective manufacturer at 
ISSCC in 1996 at the University of Texas. Here is the link:

http://www.ece.utexas.edu/~bevans/courses/ee382c/lectures/00_welcome/project2.html

Naturally, MOT presented the one about the PPC. 20mA has a long way to
go in order to reach 220mA. Also, just so you know, some of the newer
PPC chips rate *WAY* at over 550mA. 

 
> That is irrelevant to what I was discussing.  I was talking about
> damaging an IC not a person...  

Is it really? Last year, 9 people died in the UK alone from touching 9V
batteries to their tongues.... Sounds freaky and it may be, But, then
again, electricity *is* freaky.
 
> > > and...
> > > 
> > > 2. The chip is more then likely a BGA package.  Have fun finding the
> > > pins on that one...  Not all boards have one VIA per pin for BGA
> > > packages, it may not be necessary for the particular layout of the
> > > board.
> > 
> > Back when those things were made, BGA packaging (As far as the number of
> > lines that could pick/place BGA) was limited. At that time, BGA was used
> > when thermal was an issue. With this processor,thermal is not an issue.
> > Look at the specs to the chip. Further, the chances are it's not a BGA
> > unless is was manufactured before 24 months ago. The facts are that less
> > than 5% of all silicon produced before about 24 months ago was packaging
> > other than BGA. Even today, less than 9% of all silicon produced is in
> > BGA packaging. 
> 
> If its a Motorola PPC chip there is a 100% chance of it being a BGA.
> Just take a look at their web page.  There is also a pretty high chance
> of it being a BGA if its an ARM chip as well.  They are all going to BGA
> packages because they are smaller, and have a larger number of pins in a
> smaller package to give you higher IO counts.  Almost every high pin
> count device on a motherboard these days is a BGA. Just take a look for
> yourself.  I do not care for statistics, I only care about what I
> observe.  And I am observing more and more chips going to the BGA type
> package.  Hell you can even get resistor networks in BGA packages now. 
> I do not know where you got your numbers from, but as far as I am
> concerned more then 9% of all the chips I care about (not all the chips,
> but only a subset of the "all silicon" number you quoted above) are
> BGA's now.  Almost every 32bit processor Motorola makes is in a BGA, and
> even a large portion of Intel's embedded processors are BGA.  This is
> making it harder and harder for the hobbyist to reverse engineer or
> otherwise develop things using these chips.  I should know, I am one.  I
> of course also use these chips for a living (I can even say I design PC
> Boards for a living now, but only using 8 bit processors, so its not
> relevant to this discussion...), so its not like I am discussing this
> from a hobbyist perspective.


If you design boards then you know that MOT began offering PPC chips in
BGA only 24 months ago. They were forced into it due to thermal
considerations. Up until that time, they offered them in many package
formats. Further, it was such a big deal that MOT published legacy
upgrade manuals to go from the TQFP to the BGA footprint. Here is an
example of such a manual:

"Upgrading MC68328 or MC68EZ328 System CPU to MC68VZ328" Copyrighted and
published in 2000 by MOT. You can get it here:


http://e-www.motorola.com/brdata/PDFDB/docs/AN1847.pdf

Best regards


Marvin Dickens



 


 This is a digitally signed message part