DS481TMX/NOPB

Overview

The DS481TMX/NOPB is a low-power RS-485/RS-422 multipoint transceiver manufactured by Texas Instruments. It features one driver and one receiver, operating from a single +5V supply with a maximum data rate of 2.0 Mbps. The device supports up to 64 transceivers on the bus due to its half-unit load input characteristic. Key electrical parameters include a typical quiescent current of 200 μA and a sleep mode current of 0.2 μA. It operates within an industrial temperature range of -40°C to +85°C and is housed in an 8-pin SOIC package.

Feature Summary

• Automatic sleep mode reduces supply current to ultra-low levels during inactivity
• Half-unit load receiver input allows connection of up to 64 nodes on a single bus
• Integrated short-circuit current limiting and thermal shutdown for driver protection
• Failsafe receiver guarantees a logic-high output when inputs are open

Applications

• Multipoint RS-485 communication networks
• RS-422 point-to-point or multipoint links
• Industrial automation systems requiring low power consumption
• Battery-powered instrumentation with extended standby requirements

Procurement Notes

Verify component authenticity through authorized distributors as the device status is LIFEBUY. Confirm that the ordering suffix /NOPB indicates lead-free and RoHS compliance. Ensure the SOIC-8 package variant matches the required PCB footprint. Check for lifetime buy availability windows if long-term supply is needed for existing designs.

Selection Notes

Select this component for applications requiring half-unit load capability to maximize node density without repeaters. Compare against standard unit load devices if fewer than 32 nodes are needed. Verify that the 2.0 Mbps data rate meets system timing requirements. Consider the automatic sleep feature for power-sensitive designs where bus idle time is significant.

Part Context

This part belongs to the DS481 family of low-power transceivers. It is functionally compatible with the MAX481C and MAX481E. The TMX suffix denotes tape and reel packaging for automated assembly. It serves as a legacy interface solution for serial communication buses in industrial environments.

Replacement Considerations

Direct functional equivalents include the DS481TM/NOPB in tube packaging. Other Texas Instruments RS-485 transceivers may require pinout verification. Ensure substitute parts support the half-unit load specification if high node counts are required.

FAQ

How is the automatic sleep mode activated?

Sleep mode activates when both the Driver Enable (DE) pin is held LOW and the Receiver Enable (RE) pin is held HIGH for greater than 600 ns.

What is the maximum number of transceivers supported on the bus?

The DS481 has a half-unit load input, allowing up to 64 transceivers on a single bus compared to the standard 32 for full unit load devices.

Does the device have failsafe protection?

Yes, the receiver includes a failsafe feature that guarantees a logic-high output if the differential input voltage is zero or the inputs are open circuit.