RS-485/422 Data Transceivers – allow 50 nodes on a bus

Intersil announce two ultra-high-speed LinearLink RS-485/422 serial data transceivers, the ISL4486 and ISL81486. Both ICs are half-duplex configurations that operate from a nominal 5V supply over a wide 10% tolerance voltage range of +4.5 to +5.5 V, which relaxes supply requirements and reduces costs.

The ISL4486 provides an ultra-fast 40 Mbps data rate and an industry-leading 2.5V differential signal into a 54 Ohm load. The ISL81486 delivers 30 Mbps and a 2.3V differential output voltage. Both circuits are rated as 0.6-unit load transceivers that allow 50 nodes on a bus compared to the usual single-unit load allowance of only 32 nodes.

Applications for these half-duplex transceivers include, but are not limited to, Profibus DP or FMS for factory automation, SCSI 'Fast 40'and 'Fast 20' drivers and receivers, Field Bus networks, security networks, process control, plant environmental control and remote sensing and metering. The ultra-high data rates and large differential output voltages make these transceivers ideal for Profibus applications where speed, reach and data integrity are essential. They are ideal for parallel applications such as high-speed SCSI systems, due to low data skewing and part-to-part performance consistency.

The ISL4486 and ISL81486 are half-duplex transceivers whose receive (Rx) and transmit (Tx) functions are multiplexed, reducing package size and pin count to only 8-leads. Rx inputs feature a fail-safe-if-open design, which ensures a logic high Rx output if Rx inputs are floating. This prevents the Rx output from chattering, and accidentally generating interrupts, if the receiver becomes disconnected from the bus.

Driver outputs are short circuit protected, even for voltages that exceed the supply voltage. Additionally, on-chip thermal shutdown circuitry disables the Tx outputs to prevent damage if power dissipation becomes excessive.

Intersil Europe Sarl, 1006 Lausanne, Switzerland.

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