ISL81487EIBZ

These Intersil RS-485/RS-422 devices are ESD protected,fractional unit load (UL), BiCMOS, 5V powered, singletransceivers that meet both the RS-485 and RS-422standards for balanced communication. Each driver output/receiver input is protected against ±15kV ESD strikes,without latch-up. Unlike competitive devices, this Intersilfamily is specified for 10% tolerance supplies (4.5V to 5.5V).All devices present a 1/8 “unit load” to the RS-485 bus,which allows up to 256 transceivers on the network for largenode count systems (e.g., process automation, remotemeter reading systems). In a remote utility meter readingsystem, individual (apartments for example) utility meterreadings are routed to a concentrator via an RS-485network, so the high allowed node count minimizes thenumber of repeaters required to network all the meters. Datafor all meters is then read out from the concentrator via asingle access port, or a wireless link. Slew rate limited drivers on the ISL8487E and ISL81487Lreduce EMI, and minimize reflections from improperlyterminated transmission lines, or unterminated stubs inmultidrop and multipoint applications. Data rates up to250kbps are achievable with these devices.Data rates up to 5Mbps are achievable by using theISL81487E, which features higher slew rates.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 forvoltages exceeding the power supply voltage. Additionally,on-chip thermal shutdown circuitry disables the Tx outputs toprevent damage if power dissipation becomes excessive.These half duplex devices multiplex the Rx inputs and Txoutputs to allow transceivers with Rx and Tx disablefunctions in 8 lead packages.

• ±15kV ESD protected, 1/8 unit load, 5V, low power, high speed RS-485/RS-422 transceiver
• Fractional unit load allows up to 256 devices on the bus
• High data rate up to 5Mbps
• Low quiescent supply current 420µA (maximum)
• Common mode input voltage range -7V to +12V
• Three state Rx and Tx outputs
• 30ns propagation delays, 5ns skew
• Half duplex pinouts
• Operate from a single +5V supply (10% tolerance)
• Current limiting and thermal shutdown for driver overload protection