ADM1485AR-REEL

Overview

The ADM1485AR-REEL is a 5 V low power EIA RS-485 transceiver fabricated on BiCMOS technology. It supports data rates up to 30 Mbps and operates from a single 5 V supply with a typical operating current of 2.2 mA. The device features independent driver and receiver controls, providing high-Z outputs when disabled or powered off. It includes thermal shutdown protection that activates at 150°C and short-circuit protection for the driver outputs. The component accommodates a bus common-mode range from -7 V to +12 V and complies with both RS-485 and RS-422 standards.

Feature Summary

• Thermal shutdown circuitry protects against excessive power dissipation during fault conditions by disabling driver outputs.
• Fail-safe receiver feature ensures a logic high output state when inputs are unconnected or floating.
• High output impedance when disabled minimizes loading effects on the multipoint bus transmission line.

Applications

• Low Power RS-485 Systems
• DTE-DCE Interface
• Packet Switching
• Local Area Networks

Procurement Notes

Verify the specific package variant matches the design requirements, as the base model number covers multiple packaging options including SOIC and MSOP. Confirm the ordering suffix indicates the correct reel quantity and RoHS compliance status required for the manufacturing process. Ensure the industrial temperature grade is selected if operation outside commercial limits is necessary.

Selection Notes

Select this component for applications requiring bidirectional data communication on multipoint buses with high-speed capabilities. Consider the -40°C to +85°C operating range for industrial environments. Verify that the system topology allows only one driver to be enabled at any time to prevent bus contention issues.

Part Context

This part belongs to the ADM1485 series of differential line transceivers designed for balanced data transmission. It serves as a superior upgrade to the LTC1485, offering enhanced switching speeds and lower power consumption while maintaining compatibility with standard RS-485 network architectures.

Replacement Considerations

The datasheet identifies the ADM1485 as a direct superior upgrade for the LTC1485. Designers replacing older components should verify pinout compatibility and ensure the new thermal characteristics align with the existing heat dissipation strategy.

FAQ

How does the device handle bus contention?

The ADM1485 prevents excessive power dissipation caused by bus contention through its thermal shutdown circuit, which forces the driver output into a high impedance state upon detecting significant temperature increases.

What is the fail-safe behavior of the receiver?

The receiver includes a fail-safe feature that guarantees a logic high output state if the inputs are open circuit or floating, ensuring predictable behavior in disconnected states.

Can multiple transceivers be connected to the same bus?

Yes, up to 32 transceivers may be connected simultaneously on a bus, provided that only one driver is enabled at any given time to maintain signal integrity.