Atmel SpaceWire Router SpW-10X - Manual (Page 141)

Ref.: UoD_SpW-10X_
UserManual
Issue: 3.4
SpW-10X
SpaceWire Router
User Manual Date: 11 th
July 2008
Preliminary
141
2. LVDS fail safe resistors need not be adjacent to the termination resistor. Their location is
not critical but the stub lengths to the termination resistors should be less than 20 mm.
3. LVDS tracks shall be 100 ohm differential impedance.
4. Skew between the plus and minus sides of the LVDS differential pair shall be avoided and
shall be less than +/- 1 mm.
5. Data and strobe track lengths shall be matched to +/- 2.5 mm to keep skew to a minimum.
6. There is no need to match input and output track lengths.
7. Vias shall only be used at the SpaceWire connector and close to the SpW-10X device
(within 5 mm).
12.2.7 External Ports
The following recommendations apply to the External FIFO port signals from the SpW-10X device:
1. When the External FIFO ports are used, series termination resistors (33 ohm) should be used
on each output if the tracks on the outputs are more than 4 cm in length.
2. The series termination resistors should be placed as close as possible to the output pins of the
SpW-10X device.
3. Series termination resistors are also recommended on the devices driving the External FIFO
port inputs if the tracks connected to the inputs are more than 4 cm in length.
4. The pull up/down resistor recommendations provided in section 5.3 should be followed.
12.2.8 Time-code Interface
The following recommendations apply to the Time-code signals from the SpW-10X device:
1. When the time-code interface is used, series termination resistors (33 ohm) should be fitted to
each output if the tracks on the outputs are more than 4 cm in length.
2. The series termination resistors should be placed as close as possible to the output pins of the
SpW-10X device.
3. Series termination resistors are also recommended on the devices driving the time-code
inputs if the tracks connected to these inputs are more than 4 cm in length.
4. The pull up/down resistor recommendations provided in section 5.4 should be followed.
12.2.9 Status / Power On Configuration Interface
The pull up/down resistor recommendations provided in section 5.6 should be followed for power on
configuration.