Overview
Description
The ISL8485, ISL8490, and ISL8491 RS-485 / RS-422 devices are BiCMOS 5V powered, single transceivers that meet both the RS-485 and RS-422 standards for balanced communication. Unlike competitive devices, this family is specified for 10% tolerance supplies (4. 5V to 5. 5V). The ISL8485, ISL8490, and ISL8491 feature data rates up to 5Mbps. All devices present a single unit load to the RS-485 bus, which allows up to 32 transceivers on the network. The receiver (Rx) inputs feature a “fail-safe if open” design, which ensures a logic high Rx output if the Rx inputs are floating. The 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. The ISL8490 and ISL8491 are configured for full duplex (separate Rx input and Tx output pins) applications. Half duplex configurations (ISL8485) multiplex the Rx inputs and Tx outputs to allow transceivers with Rx and Tx disable functions in 8 Ld packages.
Features
- Specified for 10% tolerance supplies
- Class 3 ESD protection (HBM) on all pins: 7kV
- High data rates: up to 5Mbps
- Single unit load allows up to 32 devices on the bus
- Low quiescent current: 500µA
- -7V to +12V common-mode input voltage range
- Three state Rx and Tx outputs (except ISL8490)
- 30ns propagation delays, 5ns skew
- Full duplex and half duplex pinouts
- Operation from a single +5V supply (10% tolerance)
- Current limiting and thermal shutdown for driver overload protection
- Pb-free plus anneal (RoHS compliant)
Comparison
Applications
Design & Development
Models
ECAD Models
Schematic symbols, PCB footprints, and 3D CAD models from SamacSys can be found by clicking on the CAD Model links in the Product Options table. If a symbol or model isn't available, it can be requested directly from SamacSys.
Support
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FAQs
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Can the ISL8485 drive a 1000 ft twisted pair cable at 5 Mbps?
Question:I am trying to use your ISL8485 to drive a 1000 ft twisted pair cable at 5 Mbps, but it is not working. This distance is much shorter than the 4000 feet limit in the RS-485 standard. Any idea what the problem might be? Answer:The problem is ...
Jan 1, 1970 -
Do we need fail-safe pull-up resistors and can we have different voltage transceivers on the same RS-485 bus?
... up on the input receiver. If your circuit is unidirectional (i.e., ISL83485 transmits to ISL8485) you need only have the fail-safe on the ISL8485 input to the receiver. If your circuit is bi-directional you will need the fail-safe on the ISL83485 receiver input and the ISL8485 ...
Jan 1, 1970