High-Speed Differential Inputs
Characteristics
High-speed differential inputs (simplified schematic)
The high-speed differential input ports have the following characteristics:
- Non-isolated ANSI/TIA/EIA-422-B differential line receiver
- -7V / +12V common mode
- 4 kV contact, 8 kV air discharge ESD protection
- Minimum pulse width: 100 nanoseconds (or better)
- Maximum 10%-90% rise/fall time: 1 µs
- Maximum pulse rate: up to 5 MHz
- Fixed termination (not removable)
- Guaranteed 'High' input state when unconnected (hardware failsafe circuit)
- HF noise filtering
The state of the port is reported through the InputState MultiCam parameter.
Compatible Drivers
The following drivers are compatible with the high-speed differential input ports:
- ANSI/EIA/TIA-422/485 differential line drivers
- Complementary TTL drivers
Electrical Circuits Examples
The following figure shows the recommended wiring diagram for a system device using RS-422 differential drivers. Applicable for fast system devices such as motion encoders operating at frequencies up to 5 MHz
The following figure shows the recommended wiring diagram for a system device using two complementary CMOS or TTL drivers. Applicable for fast system devices such as motion encoders operating at frequencies up to 5 MHz
Note. For correct operation of the above two circuits, it is mandatory to satisfy the common-mode voltage requirements of the receiver. Practically, this requirement can be achieved by the addition of one "Signal Ground" wire between each system device and the board.