Description

      The AT481, AT483, AT485, AT487–AT491, and AT1487 are low-power transceivers for RS-485 and RS-422 communication. Each part contains one driver and one receiver. The AT483, AT487, AT488, and AT489 feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, thus allowing error-free data transmission up to 250kbps. The driver slew rates of the AT481, AT485, AT490, AT491, and AT1487 are not limited, allowing them to transmit up to 2.5Mbps.

     These transceivers draw between 120μA and 500μA of supply current when unloaded or fully loaded with disableddrivers. Additionally, the AT481, AT483, and AT487 have a low-current shutdown mode in which they consume only 0.1μA. All parts operate from a single 5V supply.

     Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit.

     The AT487 and AT1487 feature quarter-unit-load receiver input impedance, allowing up to 128 AT487/AT1487 transceivers on the bus. Full-duplex communications are obtained using the AT488–AT491, while the AT481, AT483, AT485, AT487, and AT1487,are designed for half-duplex applications.

      ±15kV ESD-Protected

Applications

     Low-Power RS-485 Transceivers

     Low-Power RS-422 Transceivers

     Level Translators

     Transceivers for EMI-Sensitive Applications

     Industrial-Control Local Area Networks

Typical Operating Circuit