The ISL8308XE are BiCMOS, ESD protected, 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 products, this Intersil family is specified for 10% tolerance supplies (4.5V to 5.5V). These devices have very low bus currents (+125µA/-75µA), so they present a true “1/8 unit load” to the RS-485 bus. This allows up to 256 transceivers on the network without violating the RS-485 specification’s 32 unit load maximum, and without using repeaters. For example, in a remote utility meter reading system, individual meter readings are routed to a concentrator via an RS-485 network, so the high allowed node count minimizes the number of repeaters required. Data for all meters is then read out from the concentrator via a single access port, or a wireless link. Receiver (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 ISL83080E, ISL83082E, ISL83083E and ISL83085E utilize slew rate limited drivers which reduce EMI, and minimize reflections from improperly terminated transmission lines, or unterminated stubs in multidrop and multipoint applications. Slew rate limited drivers also prevent overshoot on the RS-485 line when the transmitter is disabled.
