CLINK3V48BT-133 National Semiconductor, CLINK3V48BT-133 Datasheet - Page 6

• Manufacturer Part Number: CLINK3V48BT-133
• Description: BOARD EVAL FOR DS90CR485, 486
• Manufacturer: National Semiconductor

Specifications of CLINK3V48BT-133

• Main Purpose: Interface, SerDes (Serializer / De-Serializer)
• Embedded: No
• Utilized Ic / Part: DS90CR485, DS90CR486
• Primary Attributes: Serializes 48 LVCMOS/LVTTL to 8 LVDS, 66 ~ 133 MHz
• Secondary Attributes: Transmits over 2 Meter 3M MDR LVDS Cable
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Unshielded twisted pair (UTP) cable construction
Connector pin assignment for low skew.
Twinax cable construction
Top-good; bottom-bad.
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Design Guidelines
Cables & Connectors
Cables
Channel Link SerDes can be used over a wide variety of balanced, 100-Ohm differen-
tial cables depending on distance and signal quality requirements. In general, twinax
or shielded twisted pair cables are recommended. Low pair-to-pair skew is the most
important parameter to consider when choosing a cable assembly for Channel Link.
•
MDR and Amphenol SKEWCLEAR® systems are commonly used. See the “Data Rate
vs. Cable Length” section for typical performance using 3M MDR cable assemblies.
•
blies may be used.
•
anced ribbon cable may be used. Use ground conductors between LVDS pairs and
avoid using end conductors for LVDS signals.
At least one ground conductor should be used in the cable to provide a known, low
impedance return path for common mode currents.
A termination resistor RL, placed as close as possible to the receiver inputs in point-
to-point applications, is required. The resistor value should be chosen to match the
differential impedance of the cable.
Connectors
SCSI-type connectors like 3M MDR and CHAMP connectors are typically used.
Connectors with differential conductors offer the highest performance, but are not
necessary in low speed or short distance applications. For single-ended connectors,
keep LVDS pins away from other signals, particularly TTL/CMOS/LVTTL/LVCMOS sig-
nals. The “+” and “-” signals of a pair should be routed on the same row in multi-row
backplane connectors to help minimize skew within the pair.
SCSI-type cables and connectors or LVDS-type cable assemblies such as the 3M™
Other high performance shielded multi-pair cables such as Infiniband/CX4 assem-
Very Short Distances (< 0.3 m): flex circuit (following correct PCB layout) or unbal-
3M MDR Cable System