Linear Technology Corporation (Linear Technology CorporatiON) introduced the LTC2862-2865, an extremely robust, high-voltage-tolerance RS485/RS422 transceiver family that protects against field failures without the need for expensive external protection devices. In an actual RS485 system, installation of cross-line faults, ground faults, or lighting-induced surge voltages may cause overvoltage conditions that exceed the absolute maximum ratings of a typical transceiver. The LTC2862-2865 has ±60V overvoltage fault protection on the data transmission line, which protects the bus pins during operation and power shutdown. Whether the circuit is transmitting, receiving, in standby, or powered off, the LTC2862-2865 can tolerate voltages within ±60V without damage, thereby enhancing the ruggedness of any typical RS485 network. This low power family supports fast 20Mbps and low EMI conversion rate limited 250kbps data rates for half-duplex and full-duplex versions.

The LTC2862-2865 family provides useful protection and reliability for a variety of RS485/RS422 applications, including industrial control, instrumentation networks, and automotive electronics. The extended ±25V input common-mode range and thorough fail-safe operation improve the reliability of data communications in environments with electrical noise and in the presence of ground loop voltage. This extended common-mode range allows the LTC2862-2865 family to send 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-100-4-2 air discharge) at the transceiver pins without latchup or damage. All other pins are protected to ±8kV HBM. Fully symmetrical receiver thresholds allow these devices to maintain good duty cycle symmetry at low signal levels and improve the receiver's noise immunity.

The LTC2862-2865 family is available in commercial, industrial and automotive temperature grades and is available in DFN and SO packages with industry standard pinouts. The 20-Mbps half-duplex version is priced at $2.35 per piece in 1,000-piece quantities. These devices provide a pin-compatible upgrade path for Linear Technology's half-duplex LT1785 and full-duplex LT1791 (250kbps ±60V fault-protected transceivers).

Photo Caption: ±60V Fault-Protected RS485 Transceiver Performance with ±25V Common Mode Range: LTC2862-2865

Overvoltage line fault protection up to ±60V

• 3V to 5.5V Supply Voltage • 20Mbps or Low EMI 250kbps Data Rate • ±15kV ESD Interface Pin, All Other Pins ±8kV

Extended common-mode range: ±25V

· Ensure fail-safe receiver operation · Supports up to 256 nodes · Separate 1.65V to 5.5V logic supply pins (LTC2865)

Temperature range: -40°C to 125°C

·Industry standard pinout