UM491 - Union Semiconductor

UM491 Slew-Rate-Limited RS-422 Transceivers

The UM488/UM491 is ±15kV electrostatic discharge (ESD)-protected, high-speed transceivers for RS-422 communication that contain one driver and one receiver. The UM491 contains an additional receiver and driver enable control. The device features fail-safe circuitry, which guarantees a logic-high receiver output when the receiver inputs are open or shorted. .

Features

fail-safe circuitry, which guarantees a logic-high receiver output when the receiver inputs are open or shorted. This means that the receiver output will be a logic high if all transmitters on a terminated bus are disabled (high impedance). The UM488/UM491 offers higher driver output slew-rate limits, allowing transmit speeds up to 2.5Mbps. The device features enhanced ESD protection. All transmitter outputs and receiver inputs are protected to ±15kV using the Human Body Model. These transceivers typically draw 375µA of supply current when unloaded, or when fully loaded with the drivers disabl.