ANSI/TIA/EIA-644-95 Electrical Characteristics of Low Voltage Differential Signaling (LVDS) Interface Circuits  AKA IEEE1596.3

RS644 balanced Low Voltage Differential Signalling (LVDS) provides an electrical specification to be used as a reference for other standards. RS644 transcievers provide significantly better performance than older standards such as RS422 or RS485
 

Low voltages differential signalling
Normally wired point to point
655Mb/s max
Drive current is 3.5mA
Voltage swing 350mV
Cable impedance 100 Ohms - circuits are normally terminated
 

On Cat-5 cable a 20 metre run should handle 100Mb/s (50 metres 50Mb/s, 20 metres 100Mb/s)