Features

• Precision Propagation Delay Over Temperature: Receiver/Driver: 18.5ns ±3.5ns
• High Data Rate: 52Mbps
• Low tPLH/tPLH Skew: Receiver/Driver: 500ps Typ
• –7V to 12V RS485 Input Common Mode Range
• Guaranteed Fail-Safe Operation Over the Entire Common Mode Range
• High Input Resistance: ž22k, Even When Unpowered
• Short-Circuit Protected
• Thermal Shutdown Protected
• Driver Maintains High Impedance in Three-State or with Power Off
• Single 5V Supply
• Pin Compatible with LTC490/LTC491
• 45dB CMRR at 26MHz

Typical Application

Description

The LTC®1686/LTC1687 are high speed, precision delay, full-duplex RS485 transceivers that can operate at data rates as high as 52Mbps. The devices also meet the requirements of RS422. A unique architecture provides very stable propagation delays and low skew over a wide common mode and ambient temperature range. The driver and receiver feature three-state outputs, with disabled driver outputs maintaining high impedance over the entire common mode range. A short-circuit feature detects shorted outputs and substantially reduces driver output current. A similar feature also protects the receiver output from short circuits. Thermal shutdown circuitry protects from excessive power dissipation. The receiver has a fail-safe feature that guarantees a high output state when the inputs are shorted or are left floating. The LTC1686/LTC1687 RS485 transceivers guarantee receiver fail-safe operation over the entire common mode range (–7V to 12V). Receiver input resistance remains ž22k when the device is unpowered or disabled. The LTC1686/LTC1687 operate from a single 5V supply and draw only 7mA of supply current.