Intersil introduced the ISL317XE family of 3.3V RS-485/RS-422 transceivers. This versatile nine-member family delivers full-featured IEC61000 ESD-protected transceivers with 20Mbps data transmission rate. The line's features include full fail-safe design and hot plug capability, full/half duplex, and three data rate options. The family's full fail-safe feature eliminates external components and ensures consistent performance when bus faults occur. The new devices come in space-saving MSOP (mini small-outline package) sizes that allow designs to drop old 8- and 14-lead SOIC transceivers. The 8-lead MSOP package provides a 50 percent board space savings over 8-lead SOIC packages and Intersil's 10-lead MSOP package saves 70 percent over old 14-lead SOIC package options.

Applications include factory automation, security networks, building environmental control systems, industrial/process control systems and automated utility meter reading systems. The ISL317XE family covers all features and configurations associated with the RS-485 protocol. Data rate options are offered to match the application speed. For low-speed applications, the family offers slew-rate-limited versions at 250kbps: ISL3170E/71E/72E, and 500kbps: ISL3173E/74E/75E. The ISL3176E/77E/78E operates up to 20Mbps for high-speed applications. 

The ISL317XE family's hot plug circuitry ensures active data on the bus won't be corrupted when the new device is connected to it. Slew-rate limited drivers reduce EMI (electromagnetic interference) and minimize reflections from improperly terminated transmission lines or unterminated stubs in multidrop and multipoint applications. Slew-rate limited versions also have receiver input filtering to reduce the impact of noise on slow input signals. All devices present a light "one-eighth unit load" to the RS-485 bus, allowing up to 256 transceivers on the network. Tx outputs and Rx inputs maintain this load even when the voltages exceed the supply voltages by as much as -7V and +9V (i.e., from -7V to +12V). Rx inputs feature a full fail-safe design, which ensures a logic high Rx output if Rx inputs are floating, shorted, or terminated but undriven. The hot plug circuitry ensures that the Tx and Rx outputs remain tri-state during power up/power down.

Driver outputs are short-circuit protected, even for voltages exceeding the power supply voltage. Also, on-chip thermal shutdown circuitry disables the Tx outputs to prevent damage if power dissipation becomes excessive. The ISL3172E/75E/78E are half duplex configurations that multiplex the receiver (Rx) inputs and driver (Tx) outputs to allow transceivers with Rx and Tx disable functions in 8-lead packages. These parts come in a standard 8-lead SOIC as well as tiny 8-lead MSOP for space-constrained applications. The ISL83070E/73E/76E are full duplex configurations with Tx/Rx enable/disable functions. All three come in 14-lead SOIC and 10-lead MSOP packages. The ISL83071E/74E/77E are configured for full duplex without the enable function (RS-422) that allows them to fit into 8-lead SOIC/MSOP packages.