The MAX481E, MAX483E, MAX485E, MAX487E–MAX491E, and MAX1487E are low-power transceivers for RS-485 and RS-422 communications in harsh environments. Each driver output and receiver input is protected against ±15kV electro-static discharge (ESD) shocks, without latchup. These parts contain one driver and one receiver. The MAX483E, MAX487E, MAX488E, and MAX489E 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 MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E are not limited, allowing them to transmit up to 2.5Mbps. These transceivers draw as little as 120µA supply current when unloaded or when fully loaded with disabled drivers (see Selection Table). Additionally, the MAX481E, MAX483E, and MAX487E have a low-current shutdown mode in which they consume only 0.5µA. 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 their outputs into a high-impedance state. The receiver input has a fail-safe feature that guaran- tees a logic-high output if the input is open circuit. The MAX487E and MAX1487E feature quarter-unit-load receiver input impedance, allowing up to 128 transceivers on the bus. The MAX488E–MAX491E are designed for full-duplex communications.
This document describes Maxim's family of low‑power RS‑485/RS‑422 transceivers, including the MAX481E, MAX483E, MAX485E, MAX487E, MAX488E, MAX489E, MAX490E, MAX491E and MAX1487E. Each part integrates a driver and a receiver, offers ESD protection up to +15 kV, and operates from a single +5 V supply.
Key features include slew‑rate‑limited drivers for error‑free transmission (up to 250 kbps for certain parts), low quiescent current (as low as 120 µA), shutdown mode with 0.5 µA consumption, and the ability to place up to 128 transceivers on a bus. The datasheet provides absolute maximum ratings, detailed electrical characteristics, switching parameters, pin descriptions, and ordering information for each package type.
| ESD Protection | +15 kV (Human Body Model) |
|---|---|
| Low Quiescent Current (MAX483E/487E/488E/489E) | 120 µA |
| Maximum Data Rate (MAX481E, MAX485E, MAX490E, MAX491E, MAX1487E) | 2.5 Mbps |
| Maximum Data Rate (MAX483E, MAX487E, MAX488E, MAX489E) | 250 kbps |
| Receiver Input Impedance (MAX487E, MAX1487E) | Quarter‑unit load, up to 128 devices on bus |
The MAX481E can transmit data at up to 2.5 Mbps.
Up to 128 MAX487E transceivers can be connected on the same bus.
In shutdown mode the MAX483E consumes only 0.5 µA.
All parts operate from a single +5 V supply.