LT1785IS8

peculiarity

• Overvoltage line fault protection up to ±60V is provided
• Pin compatible with LTC485 and LTC491
• The high input impedance supports up to 128 nodes
• No damage or latch-up due to ESD
  IEC-1000-4-2 Level 4: ±15kV air discharge
  IEC-1000-4-2 Level 2: ±4kV contact discharge
• Controlled slew rate for EMI emissions control
• For floating, shorted, or standby inputs, the receiver output is guaranteed to be high
• When turned off or powered down, the output is in a high impedance state
• Drive low-cost, low-impedance cables
• Short-circuit protection is provided on all outputs
• With thermal shutdown protection
• Guaranteed operating performance at temperatures up to 125°C

description

LT^® The 1785/LT1791 are half- and full-duplex differential bus transceivers for RS485 and RS422 applications with on-chip protection circuitry against overvoltage faults on data transmission lines. The receiver input and driver output pins can withstand voltage faults up to ±60V relative to ground without damaging the device. Faults can occur when the transceiver is in operation, shutdown, or power-off state.

A data rate of 250kbaud can be supported on a network of up to 128 nodes. A controlled slew rate on the driver output is used to control EMI emissions and improve data transmission integrity on improper termination routes. The driver's specifications require that it operate with inexpensive cables with characteristic impedances as low as 72Ω.

The LT1785A/LT1791A devices feature a "fail-safe" receiver input designed to ensure that the receiver output is high for shorted, open, or standby data lines. Built-in ESD protection circuitry eliminates the need for external protection devices.

The LT1785/LT1785A are available in 8-lead DIP and SO packages, while the LT1791/LT1791A are available in 14-lead DIP and SO packages.