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

Dec 21 2011 -MILPITAS, CA
  • Linear Technology Corporation introduces 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 fail-safe 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. For more information, visit www.linear.com/product/LTC2862.

    Summary of Features: 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

    ±60V Fault Protected RS485 Transceiver with ±25V Common-Mode Range


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