DS485TM

Overview

The DS485TM is a low-power RS-485/RS-422 multipoint transceiver manufactured by Texas Instruments. It integrates one driver and one receiver, supporting data rates up to 2.5 Mbps with a typical driver transition time of 25 ns. The device operates from a single +5V supply (4.75V to 5.25V) and draws 200 μA quiescent current. It features TRI-STATE outputs, short-circuit current limiting, and thermal shutdown protection. The receiver includes a failsafe feature ensuring a logic-high output for open inputs. Characterized for industrial temperature range operation (-40°C to +85°C), it supports up to 32 transceivers on the bus across a -7V to +12V common-mode voltage range.

Feature Summary

• Low power consumption with 200 μA typical quiescent current
• Half-duplex flow-through pinout compatible with MAX485 and LTC485
• Thermal shutdown and short-circuit current limiting for driver overload protection
• Failsafe receiver ensures logic-high output when inputs are open

Applications

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

Procurement Notes

Verify the specific ordering suffix to confirm the package type and temperature range. The 'TM' suffix indicates an SOIC package with industrial temperature ratings. Confirm RoHS compliance status as some variants may differ. Check for lifetime buy availability since TI has announced discontinuation for this family. Ensure the datasheet revision matches the design requirements before finalizing procurement orders.

Selection Notes

Select the DS485TM for applications requiring standard unit loads and compatibility with existing MAX485 designs. Consider alternative devices like the DS36C278 series if reduced unit loads or higher node counts exceeding 32 are required. Verify that the 2.5 Mbps maximum data rate meets the system timing constraints. Ensure the operating temperature range aligns with the environmental conditions of the target application.

Part Context

The DS485 belongs to Texas Instruments' legacy low-power RS-485 transceiver family. It serves as a direct pin-and-functional replacement for National Semiconductor's MAX485 and Linear Technology's LTC485. This component is part of a broader portfolio that includes ultra-low power variants and auto-sleep mode devices designed for extended battery life in multipoint serial communication environments.

Replacement Considerations

The DS485M is the commercial temperature version of this component. For enhanced performance, consider the DS36C278T for ultra-low power or the DS36C279T for auto-sleep functionality. These alternatives offer different unit load specifications allowing for more than 32 nodes on the bus while maintaining pin compatibility.