STMicroelectronics Inc. (Geneva, Switzerland) introduced a pair of low-power, high-speed transceivers for RS-485 and RS-422 communication in multi-point transmission networks, and in LANs in control systems that are also suitable as level translators and transceivers in EMI-sensitive applications. Intended for data rates of up to 25Mbps, the ST490A full-duplex and ST485A half-duplex transceivers contain one driver and one receiver, which allows them to draw a typical current of 5mA when unloaded or full loaded with disabled drivers.
Each driver is short-circuit, current-limited and is protected against excessive power dissipation by thermal shutdown circuitry that puts the driver outputs into a high-impedance state. The driver can also maintain high impedance when tri-stated or when the power is off. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is an open circuit. The ICs operate from a single 5V supply and feature a common-mode, input-voltage range of -7V to +12V with a typical input hysteresis of 70mV. The devices are available in eight-pin DIP or SO08 packages and are protected from static discharges of up to 4kV.
