IEI Integration ICE-DB-9S - Manual (Page 47)

ICE Module
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CH7021A Chrontel SDTV / HDTV Transmitter http://www.chrontel.com
CH7308A Chrontel LVDS Transmitter http://www.chrontel.com
CH7307C Chrontel DVI Transmitter http://www.chrontel.com
CH7312 Chrontel DVI Transmitter http://www.chrontel.com
CX25905 Conexant DVI-D / TV / CRT Transmitter http://www.conexant.com
SiL1362/1364 Silicon Image DVI Transmitter http://www.siliconimage.com
SiL 1390 Silicon Image HDMI Transmitter http://www.siliconimage.com
4.1.4 PEG_ENABLE#
PEG_ENABLE# is defined on the COM Express connector as a method to configure
the COM Express PCIe lanes 16 through 32 on the C-D connector as a PCI Express
Graphics port, for use with an external graphics device. The usual effect of pulling
PEG_ENABLE# low is to disable the on-Module graphics engine. For some Modules,
it is possible to configure the Module such that the internal graphics engine remains
active, even when the external PEG interface is being used for a Carrier Board
graphics device. This is Module dependent. Check with your vendor. ICE Modules
implement the auto-detect function. So, please reserve this pin for future use.
4.1.5 PCI Express Test Points and Probing
IEI follows the suggestion provided by Intel® to preserve 0-Ω on the baseboard.
Additional test structures were not included in the simulation sweeps that this
guideline is based on. The inclusion of test points and probing structures has the
ability to impact the loss and jitter budgets of a PCI Express interconnect. This is not to
say that they cannot be tolerated. In general, test points and probe structures should
not introduce stubs on the differential pairs or cause significant deviation from the
recommendations given throughout this chapter. Existing vias, pads or pins should be
used wherever possible to accommodate such structures. Careful consideration must
be taken whenever additional probing structures are used.
The PCI Express based specification requires the data eyes to be measured into a
50-Ω resistor terminated to ground. To facilitate the measurement, an additional test
structure may be required on a test board. This test structure should not be included in
a production board because it will affect the overall signal quality and resulting
margins. The three-pad test structure consists of the footprints of two resistors,
perpendicular to each other forming a “L” shape. The resistor package/footprint should