ADM1485JRZ

Overview

The ADM1485JRZ is a single half-duplex RS-485 transceiver manufactured by Analog Devices Inc. in an 8-lead SOIC package. It operates from a single 5 V power supply with a typical operating current of 2.2 mA when enabled and 1 mA when disabled. The device supports data rates up to 30 Mbps, featuring driver propagation delays of 10 ns and receiver propagation delays of 15 ns. It provides a bus common-mode range from –7 V to +12 V and includes thermal shutdown protection against excessive power dissipation.

Feature Summary

• Complies with EIA RS-485 standards for balanced multipoint bus transmission
• Features high output impedance when disabled or powered down to minimize bus loading
• Includes thermal shutdown circuitry that disables the driver during fault conditions
• Receiver incorporates fail-safe logic to ensure a high output state if inputs are floating

Applications

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

Procurement Notes

Verify the specific ordering suffix to confirm the package type and temperature rating. The 'J' designation indicates the commercial temperature range (0°C to 70°C), while 'A' denotes industrial (-40°C to +85°C). Ensure the RoHS compliance status matches project requirements before finalizing procurement orders.

Selection Notes

Select this component for applications requiring high-speed bidirectional communication on multipoint buses. Verify that the system operates within the specified 5 V supply voltage limits. Consider the thermal management requirements due to the BiCMOS process and potential short-circuit currents when designing the PCB layout.

Part Context

The ADM1485JRZ belongs to the ADM1485 series of low-power RS-485 transceivers. It serves as a superior upgrade alternative to the LTC1485 model. The series is fabricated using a BiCMOS process that combines low-power CMOS with fast-switching bipolar technology to achieve high performance.

Replacement Considerations

The datasheet identifies the ADM1485 as a direct superior upgrade for the LTC1485. Other members of the ADM1485 family, such as the ADM1485ARZ, offer identical electrical specifications but differ in package style or temperature range.

FAQ

What happens to the driver outputs when the device is powered down?

The driver outputs maintain a high impedance state when powered down, which minimizes the loading effect on the bus.

How does the device protect against excessive power dissipation?

A thermal shutdown circuit detects significant temperature increases in the internal driver circuitry during fault conditions and forces the driver output into a high impedance state.

What is the fail-safe feature of the receiver?

The receiver guarantees a logic high output state if the differential inputs are unconnected or floating.