MAX485 IC Pinout, Datasheet, Circuit and Application

The MAX485 IC, designed by Analog Devices, Inc., is a highly efficient low-power transceiver for RS-485/RS-422 communication. Renowned for its reliability in long-distance serial communication, the MAX485 integrates both driver and receiver functionalities into a single 5V powered device. This IC supports various data transmission speeds, up to 2.5 Mbps with non-limited drivers and 250 kbps with slew-rate-limited drivers. Its versatile design is characterized by low quiescent current consumption, robust ESD protection, and a fail-safe receiver, making it an ideal choice for industrial automation, level translation, and environments sensitive to electromagnetic interference (EMI).

This article provides an in-depth look at the MAX485’s pinout, absolute maximum ratings, circuit examples, and diverse applications, offering a comprehensive resource for engineers and designers working with this essential communication component.

What is MAX485

The MAX485 is a low-power RS-485/RS-422 transceiver designed by Analog Devices, Inc. for reliable serial communication over long distances. This device features a single driver and receiver, operating from a single 5V supply. Its design supports data transmission speeds up to 2.5 Mbps with non-limited slew rates or 250 kbps with slew-rate-limited drivers. The MAX485 is highly efficient, drawing between 120µA and 500µA of quiescent current, and includes features such as short-circuit current limiting, thermal shutdown for driver overload protection, and a fail-safe receiver that guarantees a logic high output in case of an open circuit. It is ideal for applications in industrial automation, level translation, and EMI-sensitive environments due to its robustness and low power consumption.

The MAX485 is available in various packages and provides flexibility in communication systems, including half-duplex and full-duplex configurations with other compatible devices. Its versatility and reliable performance make it suitable for a wide range of uses, from industrial control networks to long-distance data transmission. Enhanced versions like the MAX485E offer additional electrostatic discharge (ESD) protection, ensuring resilience in high-ESD environments, but the MAX485 remains a dependable choice for standard communication needs.

Features of MAX485

• Low Quiescent Current (120µA to 500µA)
• -7V to +12V Common-Mode Input Voltage Range
• Three-State Outputs
• Supports Up to 32 Transmitters on a Bus
• Operates from a Single 5V Supply
• Current Limiting and Thermal Shutdown for Driver Overload Protection
• Low Power Consumption (Shutdown Current of 0.1µA)
• Slew-Rate-Limited Drivers (MAX483/MAX487/MAX488/MAX489)
• Data Rate up to 250kbps (Up to 2.5Mbps with Unlimited Drivers)
• Integrated Short-Circuit Current Limiting
• Integrated Thermal Shutdown
• Receiver Fail-Safe Guarantees Logic High for Open Circuit
• 48kΩ Receiver Input Resistance
• 1/4 Unit Loading on MAX487/MAX1487 (Supports Up to 128 Devices on a Single Bus)

MAX485 Pinout

Pin Configuration

The MAX485 is a low-power transceiver designed for RS-485 communication. It is widely used in industrial networks and automation systems for reliable data transmission over long distances. The IC operates with a single 5V supply and includes both driver and receiver functionalities.

ABSOLUTE MAXIMUM RATINGS

The MAX485 is designed to operate within specific limits to ensure its reliability and longevity. The absolute maximum ratings define the boundaries beyond which the device may be damaged or may not operate as intended. These ratings include supply voltage, input and output voltages, power dissipation, and temperature ranges.

MAX485 Typical Circuit

MAX485 Test Circuits Schematic

Driver DC Test Load

Receiver Timing Test Load

Driver/Receiver Timing Test Circuit

Driver Timing Test Load

Modules Based on MAX485

When working with Arduino and RS485 communication, there are two common types of modules based on the MAX485 IC. These modules allow you to interface RS485 signals with TTL logic levels, making them ideal for long-distance serial communication projects.

1. Basic MAX485 Module with Manual Direction Control

This is a straightforward MAX485 module featuring input and output pins for direct interfacing with your microcontroller. The module includes TX (Transmit) and RX (Receive) signals, along with RE (Receiver Enable) and DE (Driver Enable) control pins. In this setup, you must manually control the RE and DE pins to switch between sending and receiving data. This provides flexibility but requires additional programming effort to manage the communication direction.

2. MAX485 Module with CD4069 Hex-Inverter for Automatic Direction Control

This module integrates a CD4069 hex-inverter IC alongside the MAX485. The CD4069 is a logic inverter with six input and output pins that automatically handles the RE and DE control pins of the MAX485. The inverter ensures that when data is transmitted or received, the corresponding RE and DE pins are automatically activated, simplifying the module's operation. This type of module is especially useful when ease of use and reduced programming complexity are priorities, as it removes the need for manual direction control.

MAX485-CD4069 module schematic

MAX485 Application Details

The MAX485 is a versatile transceiver optimized for low-power, high-performance RS-485 and RS-422 communication. Its applications are broad and cover various industrial and network scenarios where reliable data transmission and low electromagnetic interference (EMI) are critical. Below are detailed descriptions of its applications:

1. Low-Power RS-485 Transceivers

The MAX485 is commonly used in RS-485 networks, which require reliable data transmission over long distances in harsh environments. Its low power consumption makes it ideal for applications where energy efficiency is crucial, such as in battery-operated devices and remote monitoring systems.

2. Low-Power RS-422 Transceivers

In RS-422 communication systems, the MAX485 provides similar benefits as in RS-485, offering low-power operation while ensuring data integrity across distances. This makes it suitable for use in point-to-point and point-to-multipoint communication setups within industrial environments.

3. Level Translators

The MAX485 can be used as a level translator in mixed-voltage systems, enabling communication between devices operating at different voltage levels. Its ability to interface with 5V systems makes it a practical choice for integrating older equipment with newer, low-voltage devices.

4. Transceivers for EMI-Sensitive Applications

The MAX485's design minimizes electromagnetic interference, making it ideal for use in EMI-sensitive environments, such as medical devices, precision instrumentation, and other applications where signal integrity is paramount.

5. Industrial-Control Local Area Networks

In industrial automation, the MAX485 is employed in local area networks (LANs) to connect various control systems, sensors, and actuators. Its robustness and reliability ensure seamless communication across different components of an industrial control system, even in electrically noisy environments.

Package Dimensions

MAX485 Datasheet PDF

Download MAX485 Datasheet PDF>>

What is the Difference between MAX485 and MAX485E?

The MAX485E is an enhanced version of the MAX485, primarily distinguished by its superior electrostatic discharge (ESD) protection. While both transceivers offer similar performance in RS-485/RS-422 communication, the MAX485E is designed for use in environments where ESD protection is critical.

Manufacturer

The MAX485 is manufactured by Analog Devices, Inc. (formerly produced by Maxim Integrated). Analog Devices, Inc. is a global leader in the design and manufacturing of semiconductor products, known for its innovation and high-quality solutions in analog and mixed-signal processing. With a rich history of delivering cutting-edge technology, Analog Devices provides a wide range of products, including data converters, amplifiers, and power management ICs. The company has a strong reputation in the industry for its reliability and excellence, serving various sectors such as industrial automation, automotive, healthcare, and communications.

The MAX485, originally developed by Maxim Integrated, is now under the Analog Devices portfolio following their acquisition of Maxim Integrated in 2021. This acquisition has further strengthened Analog Devices' position in the market by expanding its offerings in the communication and interface ICs domain. The MAX485, a robust RS-485/RS-422 transceiver, is one of the many high-performance products that exemplify Analog Devices' commitment to quality and innovation, making it a trusted choice for engineers and designers in various industries.

Conclusion

In summary, the MAX485 IC stands out for its blend of low power consumption, high performance, and reliability in challenging communication environments. Whether used in industrial control systems, level translators, or EMI-sensitive applications, the MAX485 delivers dependable data transmission and robust protection features.

As part of Analog Devices' extensive portfolio, the MAX485 exemplifies the company's commitment to innovation and quality in semiconductor technology. By understanding its pin configuration, maximum ratings, and typical circuit implementations, users can effectively leverage the MAX485 for a wide range of applications, ensuring optimal performance and reliability in their communication systems.

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