ISL3178E

The Renesas ISL317xE are ±15kV IEC61000 ESD protected, 3. 3V powered single transceivers that meet both the RS-485 and RS-422 standards for balanced communication. These devices have very low bus currents (+125µA/-100µA), 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 using an RS-485 network, so the high allowed node count minimizes the number of repeaters required. 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. Hot Plug circuitry ensures that the Tx and Rx outputs remain in a high impedance state while the power supply stabilizes. The ISL3170E through ISL3175E 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 versions also include receiver input filtering to enhance noise immunity in the presence of slow input signals. The ISL3170E, ISL3171E, ISL3173E, ISL3174E, ISL3176E, and ISL3177E are configured for full duplex (separate Rx input and Tx output pins) applications. The half duplex versions multiplex the Rx inputs and Tx outputs to allow transceivers with output disable functions in 8 Ld packages.