LTC1487 - Ultra-Low Power RS485 with Low EMI, Shutdown and High Input Impedance

The LTC®1487 is an ultra-low power differential line transceiver designed with high impedance inputs allowing up to 256 transceivers to share a single bus. It meets the requirements of RS485 and RS422. The LTC1487 features output drivers with controlled slew rate, decreasing the EMI radiated from the RS485 lines, and improving signal fidelity with misterminated lines. The CMOS design offers significant power savings without sacrificing ruggedness against overload or ESD damage. Typical quiescent current is only 80µA while operating and 1µA in shutdown. The driver and receiver feature three-state outputs, with the driver outputs maintaining high impedance over the entire common-mode range. Excessive power dissipation caused by bus contention or faults is prevented by a thermal shutdown circuit which forces the driver outputs into a high impedance state. The receiver has a fail-safe feature which guarantees a high output state when the iputs are left open. I/O pins are protected against multiple ESD strikes of over ±10kV using the Human Body Model. The LTC1487 is fully specified over the commercial temperature range and is available in 8-pin DIP and SO packages.

Features

High Input Impedance: Up to 256 Transceivers on the Bus
Low Power: ICC = 120µA Max with Driver Disabled
ICC = 200µA Max with Driver Enabled, No Load
1µA Quiescent Current in Shutdown Mode
Controlled Slew Rate Driver for Reduced EMI
Single 5V Supply
ESD Protection to ±10kV On Receiver Inputs and Driver outputs
-7V to 12V Common-Mode Range Permits ±7V Ground Difference Between Devices on the Data Line
Thermal Shutdown Protection
Power Up/Down Glitch-Free Driver Outputs Permit Live Insertion or Removal of Transceiver
Driver Maintains High Impedance in Three-State or with the Power Off
Pin Compatible with the LTC485