Features

• Precision Propagation Delay Over Temperature: Receiver/Driver: 18.5ns ±3.5ns
• High Data Rate: 52Mbps
• Low t_PLH/t_PHL Skew: Receiver/Driver: 500ps Typ
• –7V to 12V RS485 Input Common Mode Range
• Guaranteed Fail-Safe Receiver Operation Over the Entire Common Mode Range
• High Receiver Input Resistance: >/=22k, 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 LTC485
• 45dB CMRR at 26MHz

Typical Application

Description

The LTC®1685 is a high speed, precision delay RS485 transceiver that can operate at data rates as high as 52Mbps. The device also meets 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 LTC1685 RS485 transceiver guarantees receiver fail-safe operation over the entire common mode range (–7V to 12V). Input resistance will remain >/=22k when the device is unpowered or disabled. The LTC1685 operates from a single 5V supply and draws only 7mA of supply current.