Kontron COMe Starterkit Eval T2 - Manual (Page 206)

Appendix A: Deprecated Features
9.1.4. Routing Considerations
At least 30mils of spacing should be used for the routing between each TV-DAC channel to
prevent crosstalk between the TV-DAC signals. The maximum trace length distance of the TV-
DAC signals between the COM Express connector and the 150Ω ±1% termination resistor should
be within 12 inches. This distance should be routed with a 50Ω trace impedance.
9.1.5. Signal Termination
Each of the TV-DAC channels should have a 150Ω ±1% pull-down termination resistor connected
from the TV-DAC output of the COM Express Module to the Carrier Board ground. This
termination resistor should be placed as close as possible to the TV-Out connector on the Carrier
Board. A second 150Ω ±1% termination resistor exists on the COM Express Module itself.
9.1.6. Video Filter
There should be a PI-filter placed on each TV-DAC channel output to reduce high-frequency
noise and EMI. The PI-filter consists of two 10pF capacitors with a 120Ω @ 30Mhz ferrite bead
between them. It is recommended to place the PI-filters and the termination resistors as close as
possible to the TV-Out connector on the Carrier Board. The PI-filters should be separated from
each other by at least 50mils or more in order to minimize crosstalk between the TV-DAC
channels.
9.1.7. ESD Protection
ESD clamp diodes are required for each TV-DAC channel. These low capacitance clamp diodes
should be placed as near as possible to the TV-Out connector on the COM Express Carrier
Board between +5V supply voltage and ground.
PICMG ® COM Express ® Carrier Board Design Guide Rev. 2.0 / December 6, 2013
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