DS485M

Overview

The DS485M is a low-power RS-485/RS-422 multipoint transceiver manufactured by Texas Instruments. It integrates one driver and one receiver, operating from a single +5V supply with a typical quiescent current of 200 μA. The device supports data rates up to 2.5 Mbps and features a half-duplex flow-through pinout. Electrical characteristics include a common-mode input voltage range of -7V to +12V, short-circuit current limiting, and thermal shutdown protection. It is available in an 8-pin SOIC package and is characterized for the industrial temperature range of 0°C to +70°C.

Feature Summary

• Supports up to 32 standard unit loads on the bus across the full common-mode voltage range
• Includes failsafe receiver logic that ensures a logic-high output when inputs are open circuit
• Driver outputs enter TRI-STATE under fault conditions due to thermal shutdown protection

Applications

• Multipoint RS-485 communication networks
• Industrial process control systems
• Building automation applications

Procurement Notes

Verify the specific ordering suffix against the latest TI Package Option Addendum to confirm lead finish and environmental compliance. Confirm the lifetime-buy status and availability window before finalizing procurement plans. Ensure the selected package variant matches the required PCB footprint and soldering profile specifications.

Selection Notes

Select this component for designs requiring standard RS-485 compatibility with minimal power consumption. Verify that the application operates within the specified 0°C to +70°C temperature range. Ensure the system design accommodates the 2.5 Mbps maximum data rate limit based on cable length and transition time ratios.

Part Context

The DS485M belongs to the DS485 family of low-power transceivers originally developed by National Semiconductor and acquired by Texas Instruments. This series provides pin-and-functional compatibility with industry-standard parts like the MAX485 and LTC485, facilitating direct replacements in existing hardware designs without schematic modifications.

Replacement Considerations

DS485MX/NOPB (Reel packaging)

FAQ

How does the DS485 handle bus contention?

The device features short-circuit current limiting and thermal shutdown protection. If excessive power dissipation occurs due to contention, the thermal shutdown circuit places the driver outputs into a TRI-STATE condition.

What is the failsafe feature of the receiver?

The receiver includes a failsafe feature that ensures a logic-high output if the differential input voltage is zero, which occurs when the input pins are open circuit or non-terminated.