ISL81487

Application

• High Node Count Networks
• Automated Utility Meter Reading Systems
• Factory Automation
• Security Networks
• Building Environmental Control Systems
• Industrial/Process Control Networks




Pinout






Specifications

VCC to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V
Input Voltages
DI, DE, RE . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to (VCC +0.5V)
Input/Output Voltages
A/Y, B/Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -8V to +12.5V
RO . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . -0.5V to (VCC +0.5V)
Short Circuit Duration
Y, Z. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
ESD Rating
HBM (Per MIL-STD-883, Method 3015.7) . . . . . . . .. . . . . . . >7kV




Description

These Intersil RS-485/RS-422 devices are fractional unit load (UL), BiCMOS, 5V powered, single transceivers that meet both the RS-485 and RS-422 standards for balanced communication. Unlike competitive devices, this Intersil family is specified for 10% tolerance supplies (4.5V to 5.5V). The ISL81483 and ISL81487 present a 1/8 unit load to the RS-485 bus, which allows up to 256 transceivers on the network for large node count systems (e.g., process automation, remote meter reading systems). The 1/4 UL ISL8487 allows up to 128 transceivers on the bus. In a remote utility meter reading system, individual (apartments for example) utility meter readings are routed to a concentrator via an RS-485 network, so the high allowed node count minimizes the number of repeaters required to network all the meters. Data for all meters is then read out from the concentrator via a single access port, or a wireless link. Slew rate limited drivers on the ISL8487 and ISL81483 reduce EMI, and minimize reflections from improperly terminated transmission lines, or unterminated stubs in multidrop and multipoint applications. Data rates up to 250kbps are achievable with these devices. Data rates up to 5Mbps are achievable by using the ISL81487, 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 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. These half duplex devices multiplex the Rx inputs and Tx outputs to allow transceivers with Rx and Tx disable functions in 8 lead packages.