Linear Technology has introduced the LTC2862-2865, a family of rugged, high voltage tolerant RS485/RS422 transceivers for elimination of field failures without the need of external protection devices.
In practical RS485 systems, installation cross wiring faults, ground voltage faults or lightning induced surge voltages can cause overvoltage conditions that exceed absolute maximum ratings of typical transceivers. The LTC2862-2865 feature ±60V overvoltage fault protection on the data transmission lines, protecting bus pins during operation and power shutdown. Whether a circuit is transmitting, receiving, in standby or powered off, the devices are designed to tolerate any voltage within ±60V without damage, increasing the robustness of any typical RS485 network. The low power family supports fast 20Mbit/s and low emi slew rate limited 250kbit/s data rates, as well as half and full duplex versions. According to Linear, the LTC2862-2865 family provides valuable protection and reliability for a wide variety of RS485/RS422 applications, including industrial control, instrumentation networks and automotive electronics. An extended ±25V input common-mode range and full failsafe operation improve data communications reliability in electrically noisy environments and in the presence of ground loop voltages. This extended common mode range allows the LTC2862-2865 devices to transmit and receive under harsh conditions that would otherwise cause data errors and possible device damage. Enhanced esd protection allows these devices to withstand ±15kV (HBM and IEC-1000-4-2 air discharge) on the transceiver pins without latchup or damage; all other pins are protected to ±8kV HBM. Fully symmetric receiver thresholds allow the devices to maintain good duty cycle symmetry at low signal levels and boost receiver noise immunity. The LTC2862-2865 range is offered in commercial, industrial and automotive temperature grades and available in DFN and SO packages with industry standard pinouts. The devices provide a pin compatible upgrade path from Linear's half duplex LT1785 and full duplex LT1791, 250kbps ±60V fault protected transceivers.