Low Power RS485 Transceiver with Carrier Detect and Receiver Fail-Safe

The LTC1482 is a low power RS485 compatible transceiver that offers an active low carrier detect output. The open-drain carrier detect pin allows several transceivers to share the same carrier detect line and can be used to detect the insertion or removal of a driven RS485/RS422 cable.

Enhanced ESD protection allows the LTC1482 to withstand ±15kV (human body model), IEC-1000-4-2 level 4 (±8kV) contact and level 3 (±8kV) air discharge ESD without latchup or damage.

The LTC1482 receiver stays alive at all times except in shutdown. The supply current is a maximum of 700µA and 900µA when the driver is disabled and enabled respectively. In shutdown, the quiescent current of the LTC1482 drops to a maximum of 20µA.

When the driver is disabled or the LTC1482 is in shutdown, the driver outputs are three-stated and remain in a high impedance state over the RS485 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 LTC1482 is fully specified over the commercial and industrial temperature ranges and is available in 8-lead MSOP, PDIP and SO packages.

Applications

* Battery-Powered RS485/RS422 Applications

* Low Power RS485/RS422 Transceiver

* Level Translator

* No Damage or Latchup to ±15kV (Human Body Model), IEC1000-4-2 Level 4 (±8kV) Contact and Level 3 (±8kV) Air Discharge

* Active Low Carrier Detect Output

* Guaranteed High Receiver Output State for Floating, Shorted or Terminated Inputs with No Signal Present

* Drives Low Cost Residential Telephone Wires

* Low Power: ICC = 700µA Max with Driver Disabled

* ICC = 900µA Max in Driver Mode Without Load

* 20µA Max Quiescent Current in Shutdown Mode

* Single 5V Supply

* –7V to 12V Common Mode Range Permits ±7V Ground Difference Between Devices on the Data Line

* Maximum Data Rate of 4Mbps

* Power Up/Down Glitch-Free Driver Outputs

* Up to 32 Transceivers on the Bus

* Available in 8-Lead MSOP, PDIP and SO Packages