ISL83490 3.3V Full Duplex 10Mbps RS-485/RS-422 Transceiver

The Intersil RS-485/RS-422 devices are BiCMOS transceivers powered by 3.3V, designed to comply with both RS-485 and RS-422 standards for balanced communication. This Intersil family is specified for a supply voltage tolerance of 10% (ranging from 3V to 3.6V). The ISL83483 and ISL83488 models utilize slew rate limited drivers, which help reduce electromagnetic interference (EMI) and minimize reflections from improperly terminated transmission lines or unterminated stubs in multidrop and multipoint applications. The receiver (Rx) inputs feature a "fail-safe if open" design, ensuring a logic high output when Rx inputs are floating. All devices present a "single unit load" to the RS-485 bus, allowing for a maximum of 32 transceivers on the network. The driver (Tx) outputs are protected against short circuits, even when subjected to voltages exceeding the power supply voltage. Additionally, on-chip thermal shutdown circuitry disables the Tx outputs to prevent damage due to excessive power dissipation. The ISL83488, ISL83490, and ISL83491 models are configured for full duplex applications, featuring separate Rx input and Tx output pins. The ISL83488 and ISL83490 are available in compact 8-lead packages for applications that do not require Rx and Tx output disable functions, such as point-to-point and RS-422. Half duplex configurations, such as the ISL83483 and ISL83485, multiplex the Rx inputs and Tx outputs, providing transceivers with Rx and Tx disable functions in 8-lead packages.

The Intersil RS-485/RS-422 family of devices is engineered to facilitate robust and reliable data communication in various industrial and commercial applications. The BiCMOS technology employed in these transceivers ensures low power consumption while maintaining high-speed performance, making them suitable for battery-operated devices and energy-efficient systems. The specified voltage tolerance range of 3V to 3.6V allows for greater flexibility in system design, accommodating variations in power supply levels.

The slew rate limited drivers incorporated in the ISL83483 and ISL83488 models are particularly advantageous in environments prone to EMI, as they help maintain signal integrity by reducing the rate of voltage change, which in turn minimizes radiated emissions. This feature is essential in applications where multiple devices share the same communication medium, as it helps to prevent crosstalk and ensures reliable data transmission.

The fail-safe design of the receiver inputs is a critical feature for ensuring system reliability. In scenarios where the Rx inputs may become disconnected or unconnected, the logic high output prevents erroneous data interpretation by downstream devices, thereby enhancing overall system robustness. The capability to connect up to 32 transceivers on the RS-485 bus is facilitated by the single unit load specification, which simplifies network design and reduces component count.

The short circuit protection of the Tx outputs is an essential safety feature that safeguards the transceiver from potential damage caused by overcurrent conditions. The integrated thermal shutdown circuitry further enhances the reliability of the device by automatically disabling the Tx outputs in the event of excessive power dissipation, thus preventing thermal damage.

The versatility of the ISL83488, ISL83490, and ISL83491 models in full duplex configurations supports a wide range of applications, from simple point-to-point connections to complex multidrop networks. The compact 8-lead packages of the ISL83488 and ISL83490 are particularly useful in space-constrained designs, allowing for efficient use of PCB real estate.

For half duplex applications, the ISL83483 and ISL83485 models provide the necessary flexibility by allowing the same pins to serve as both Rx and Tx, optimizing the design for applications where bidirectional communication is required with fewer pins. This design consideration is crucial for minimizing the footprint of the circuit while maintaining functionality and performance.

Overall, the Intersil RS-485/RS-422 family of transceivers offers a comprehensive solution for balanced communication, combining advanced features that ensure reliability, flexibility, and efficiency in a wide range of electronic applications.These Intersil RS-485/RS-422 devices are BiCMOS 3. 3V 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 (3V to 3. 6V). The ISL83483 and ISL83488 utilize slew rate limited drivers which reduce EMI, and minimiz e reflections from improperly terminated transmission lines, or unterminated stubs in multidrop and multipoint applications. Receiver (Rx) inputs feature a "fail-safe if open" design, which ensures a logic high output if Rx inputs are floating.

All devices present a "single unit load" to the RS-485 bus, which allows up to 32 transceivers on the network. 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 ISL83488, ISL83490, ISL83491 are configured for full duplex (separate Rx input and Tx output pins) applications.

The ISL83488 and ISL83490 are offered in space saving 8 lead packages for applications not requiring Rx and Tx output disable functions (e. g. , point-to-point and RS-422). Half duplex configurations (ISL83483, ISL83485) multiplex the Rx inputs and Tx outputs to provide transceivers with Rx and Tx disable functions in 8 lead packages.

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