C5621 and C33 User Guide
1/1553-KRD 131 24 Uen Rev D 2011-11-22
Ericsson AB 2011
14 (37)
Ericsson Confidential
4.2.1
Clock Routing
Must be routed with a controlled impedance (50-60 Ohm)
Should not be routed over a discontinuous GND plane
Keep clock traces as short as possible
Place serial termination close to transmitter output
Crosstalk:
o
Crosstalk falls off with the square of the distance, therefore
adequate spacing is a good method in reducing crosstalk
o
As a rule of thumb, 3xH can be used for all clock signals:
Figure 3, Spacing rule
Involved signals:
o
SYSCLK
o
RTC_CLK
o
UIM_CLK
4.2.2
USB Routing
Traces should be routed as a differential pair, matched in length.
Differential Impedance between the traces shall be 90 Ohm
Involved signals:
o
USB_DP
o
USB_DM
H
3xH
Reference plane
Aggressor
Victim
