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±60V Fault Protected Full-/Half-Duplex 3V to 5.5V RS485 Transceivers Achieve 20Mbps

29th February 2012

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Datasheet

Linear Technology has introduced the LTC2862-2865, a family of exceptionally rugged, high voltage tolerant RS485/RS422 transceivers for elimination of field failures without the need of costly 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 LTC2862-2865 tolerate any voltage within ±60V without damage, increasing the robustness of any typical RS485 network. The low power family supports fast 20Mbps and low-EMI slew-rate-limited 250kbps data rates, as well as half- and full-duplex versions.

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 family is offered in commercial, industrial and automotive temperature grades and available in DFN and SO packages with industry-standard pinouts. Pricing starts at $2.35 each for the 20Mbps half-duplex versions in 1,000 piece quantities. These devices provide a pin-compatible upgrade path from Linear’s half-duplex LT1785 and full-duplex LT1791, 250kbps ±60V fault protected transceivers.

Summary of Features of the LTC2862-65:

• Protected from Overvoltage Line Faults to ±60V

• 3V to 5.5V Supply Voltage

• 20Mbps or Low EMI 250kbps Data Rate

• ±15kV ESD Interface pins, ±8kV All Other Pins

• Extended Common-Mode Range: ±25V

• Guaranteed Failsafe Receiver Operation

• Supports up to 256 Nodes

• Separate 1.65V to 5.5V Logic Supply Pin (LTC2865)

• Temperature Range: -40°C to 125°C

• Industry-Standard Pinouts