GENERAL DESCRIPTION
The ADM3491 is a low power differential line transceiver designed to operate using a single +3.3 V power supply. Low power consumption coupled with a shutdown mode make it ideal for power sensitive applications. It is suitable for communication on multipoint bus transmission lines.
It is intended for balanced data transmission and complies with both EIA Standards RS-485 and RS-422. It contains a differential line driver and a differential line receiver, making it suitable for full duplex data transfer.
The input impedance is 19 kΩ allowing up to 50 transceivers to be connected on the bus.
Excessive power dissipation caused by bus contention or by output shorting is prevented by a thermal shutdown circuit. This feature forces the driver output into a high impedance state if, during fault conditions, a significant temperature increase is detected in the internal driver circuitry.
The receiver contains a fail-safe feature that results in a logic high output state if the inputs are unconnected (floating).
The ADM3491 is fabricated on BiCMOS, an advanced mixed technology process combining low power CMOS with fast switching bipolar technology.
The ADM3491 is fully specified over the industrial temperature range and is available in DIP and SOIC packages as well as a new space saving TSSOP package.

FEATURES
  Operates with +3.3 V Supply
  EIA RS-422 and RS-485 Compliant Over Full CM Range
  19 kV Input Impedance
  Up to 50 Transceivers on Bus
  20 Mbps Data Rate
  Short Circuit Protection
  Specified Over Full Temperature Range
  Thermal Shutdown
  Interoperable with 5 V Logic
  840 mA Supply Current
  2 nA Shutdown Current
  Also Available in TSSOP Package
  Meets IEC1000-4-4 (>1 kV)
  8 ns Skew
  Upgrade for MAX 3491, SN75ALS180
 
APPLICATIONS
  Telecommunications
  DTE-DCE Interface
  Packet Switching
  Local Area Networks
  Data Concentration
  Data Multiplexers
  Integrated Services Digital Network (ISDN)
  AppleTalk
  Industrial Controls