 |
| The
TinyBGA DIMM Specifications /
Features |
| Itsy
Bitsy.... |
|
Click
all images for full view
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3.3V
Unbuffered 168 Pin DIMM
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4K
Self Refresh
-
2K
E2 PROM for SPD (Serial Presence
Detect)
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128MB
DIMM Consisting of 16 8MX8 Synch SDRAM chips
rated at 7.5 ns
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1"
High PCB - Double Sided Component Mounting
-
CAS3
Latency - Rated at 133MHz.
Those
SDRAM chips look small don't they? Look
again...
Just
how small are they compared to a standard SDRAM
chip? TINY....
Alright
then, let's have a keen look at the obvious
here. This thing is small. The PCB
itself measures only 1" high versus most
standard modules which stack up to about an
1" and 1/4 to an 1" and 3/8ths.
The reason for this small footprint of the TinyBGA
DIMM, is the fact that it utilizes BGA packaging
for its SDRAM chips. BGA, an acronym
representing the words "Ball Grid
Array", is a type of semiconductor packaging
that utilizes tiny solder balls on the bottom of
the device versus wire leads protruding out of the
sides. This allows for a much smaller
overall chip size due to the fact that a smaller
PCB and "chip and wire" interconnect
internally to the device, can be used.
Standard TSOP (Thin Small Outline Package) SDRAM
chips utilize bulkier wire "Lead Frames"
internally and also have to incorporate leads from
the sides of the package, to connect the device to
the PCB is it mounted on. The end result is
a much larger device versus the BGA
solution. All motherboard and graphics
chipset vendors utilize BGA packaging with their
products now, since the "pin count" is
so incredibly high as devices get more and more
complex. If you had to use the old
"leaded" approach, a graphics chip would
be a huge monster of a part that would be
impractical in manufacturing or PCB space.
The
additional real estate that you will gain by going
with the TinyBGA module "could" in fact
allow you to utilize a large CPU Heatsink that
normally encroaches on a DIMM slot but now will
clear it over the top of the module. This is
only a possibility. We weren't able to
prove this out and there are lots of different
mechanical situations out there but the space
savings is only a bonus for you. Another
advantage to the smaller discrete device size on
these modules, is that you can build denser
modules, 256MB and up, in a smaller
footprint. Here is a shot to illustrate what
we mean.
The
top module is a Double Sided 256MB DIMM with 32
chips and the bottom is a 144 pin S0-DIMM (small
outline DIMM).
From
an electrical spec point of view, the TinyBGA DIMM
has several advantages due to the implementation
of the BGA packaged SDRAM chips on board.
BGAs have inherently better noise characteristics,
signal integrity and thermal efficiency, versus
their TSOP or leaded counterparts. The
following charts, courtesy of Kingmax,
illustrate the benefits pretty well.
Noise
of characteristics of TinyBGA Versus TSOP SDRAM
In
these images, the light blue line indicates noise
relative to the clock, in yellow. Notice
that the line in the TinyBGA shot has very little
skew and jitter against the base line.
Furthermore, the red line indicates the clock rise
and fall times. As you can see, the Tiny BGA has a
much more organized appearance indicative of a
cleaner signal. Overall, the TinyBGA has
significantly better signal integrity versus a
TSOP package.
With
respect to heat dissipation, the TinyBGA is
superior as well.
The
average surface temp of the TinyBGA is 93.9 versus
102.2, although we are not told at what frequency
the chips were being run, in this shot. At
any rate, it is widely known that BGA devices
dissipate heat better than leaded devices, so
we'll take their word for it.
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