st20-gp1 STMicroelectronics, st20-gp1 Datasheet - Page 71

• Manufacturer Part Number: st20-gp1
• Description: Gps Processor
• Manufacturer: STMicroelectronics

12.3 OS-Link connections
Links are TTL compatible and intended to be used in electrically quiet environments, between
devices on a single printed circuit board or between two boards via a backplane. Direct connection
may be made between devices separated by a distance of less than 300 mm. For longer distances
a matched 100 ohm transmission line should be used with series matching resistors (RM), see
Figure 12.3. When this is done the line delay should be less than 0.4 bit time to ensure that the
reflection returns before the next data bit is sent. Buffers may be used for very long transmissions,
see Figure 12.4. If so, their overall propagation delay should be stable within the skew tolerance of
the link, although the absolute value of the delay is immaterial.
OSLinkOut
OSLinkOut
OSLinkOut
OSLinkIn
OSLinkIn
OSLinkIn
Figure 12.3 OS-Links connected by transmission line
Figure 12.4 OS-Links connected by buffers
Figure 12.2 OS-Links directly connected
Zo=100 ohms
RM
buffers
Zo=100 ohms
RM
OSLinkIn
OSLinkOut
OSLinkIn
OSLinkOut
OSLinkIn
OSLinkOut
ST20-GP1
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