RS-485/RS-422 transceivers for harsh environments

EDN Europe, 15 Apr 2011

Intersil has introduced the ISL3247xE, ISL3248xE, and ISL3249xE series of robust, fault-protected RS-485/RS-422 transceivers that combine overvoltage protection (OVP), high electrostatic discharge (ESD) tolerance and wide common-mode range. Also featuring low quiescent supply current, the devices are suitable for harsh operating environment applications such as security/surveillance cameras, industrial process control and factory automation networks.
The devices offer very wide common-mode range (CMR) compared to similar competitive RS-485 devices. Driver outputs and receiver inputs are fault-protected against voltages as high as ±60V and are protected against ESD events up to ±16.5 kV, enhancing reliability in harsh environments. The devices have a quiescent supply current of 2.3 mA, which Intersil says is 30% to 50% lower than competitive devices.

The ISL3249xE and ISL3248xE series combine both ±60V OVP and ±25V CMR, while the ISL3247xE is rated at ±60V OVP and ±15V CMR. The family includes slew rate limited versions, high data rate versions and both half-duplex and full-duplex configurations. It includes full fail-safe receiver inputs ensuring a logic high receiver output if the inputs are shorted, floating or on an idle bus, eliminating the need for bus-biasing resistors. The ISL3248xE series includes a polarity reversal feature to overcome swapped cable data wires. The devices are housed in a variety of packages including 8-pin and 14-pin SOIC and 8-pin MSOP packages, and cost from $1.40 (1,000).