ISL8491E

The ISL8489E, ISL8491E devices are ESD protected, BiCMOS, 5V powered, single transceivers that meet both the RS-485 and RS-422 standards for balanced communication. Each driver output and receiver input is protected against ±15kV ESD strikes, without latch-up.

Unlike competitive versions, these Intersil devices are specified for 10% tolerance supplies (4.5V to 5.5V). These devices are configured for full duplex (separate Rx input and Tx output pins) applications, so they are ideal for RS-422 networks requiring high ESD tolerance on the bus pins. The ISL8489E utilizes a slew rate limited driver which reduces EMI, and minimizes reflections from improperly terminated transmission lines, or unterminated stubs in multidrop and multipoint applications.

Data rates up to 10Mbps are achievable by using the ISL8491E, which features higher slew rates. The devices present a "single unit load" to the RS-485 bus, which allows a total of 32 transmitters and receivers on the network. For "1/8 unit load" versions (256 devices on the bus), please refer to the ISL4489E, ISL4491E data sheet. Receiver (Rx) inputs feature a "fail-safe if open" design, which ensures a logic high Rx output if Rx inputs are floating. Driver (Tx) outputs are short circuit protected, even for voltages exceeding the power supply voltage. Additionally, on-chip thermal shutdown circuitry disables the Tx outputs to prevent damage if power dissipation becomes excessive.