Patent ID: 8027405

Claim:
A data communication system, comprising: at least three signal conductors; a first and a second power supply terminal, for supplying currents of mutually opposite direction to the signal conductors respectively; a driver circuit coupled between the power supply terminals and the signal conductors, the driver circuit being arranged to establish a combination of currents through respective ones of the signal conductors, the driver circuit configured to select successive combinations, depending on information to be transmitted, from a selectable set of combinations, at least three different current levels to any signal conductor being used in the set, including a current level of current to the signal conductors from the first power supply terminal and a current level of current from the signal conductors to the second power supply terminal, a sum of the currents through the signal conductors substantially having a same value for each combination in the set and at least one of the conductors for at least one of the combinations not merely functioning in a differential pair relation with another one of the conductors; wherein at least one of the combinations of the selectable set of combinations includes more than one of the current level of current to the signal conductors from the first power supply terminal or more than one of the current level of current from the signal conductors to the second power supply.