DS8921AM

Overview

The DS8921AM is a differential line driver and receiver pair manufactured by National Semiconductor, now part of Texas Instruments. It operates within a supply voltage range of 4.5 V to 5.5 V, with a typical operating voltage of 5 V. The device supports data rates up to 10 Mb/s and draws a maximum operating supply current of 35 mA. Designed for industrial environments, it functions reliably between -40°C and +85°C. The component is housed in an SOIC-8 surface-mount package and complies with RS-422 interface standards.

Feature Summary

• Provides a single differential driver and receiver pair for balanced transmission lines
• Features Schmitt trigger inputs on the receiver to filter noise and ensure clean signal transitions
• Designed for high-speed data communication with low skew characteristics

Applications

• RS-422 serial communication interfaces
• Industrial control systems requiring balanced line driving
• Data acquisition networks

Procurement Notes

Verify the manufacturer origin carefully, as National Semiconductor was acquired by Texas Instruments. Ensure the specific suffix matches the required temperature grade and packaging format. Confirm RoHS compliance status through official documentation, as older batches may differ from current production runs.

Selection Notes

Select this component when a single full-duplex channel is required for RS-422 applications. It is suitable for designs needing moderate speed up to 10 Mb/s with robust noise immunity provided by Schmitt triggers. Consider pin-compatible alternatives if higher integration or lower power consumption is needed.

Part Context

This part belongs to the DS8921x family of differential CMOS line drivers and receivers. It is functionally similar to other industry-standard RS-422 transceivers like the SN75179B but offers specific performance characteristics tailored for timing-critical applications. The 'A' suffix typically denotes an extended industrial temperature range.

Replacement Considerations

The SN75179B is a widely available alternative offering similar RS-422 functionality. Other compatible options include the LTC490 series from Analog Devices. Verify pinout compatibility and electrical specifications before substitution.