9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

9.1 Application Information

When using AM26LS32A as a receiver, the AM26LS31AC can allow multiple AM26LS32As to be used causing

an increase in the amount of outputs.

9.2 Typical Application

Figure 9-1 shows a configuration with no termination. Although reflections are present at the receiver inputs

at a data signaling rate of 200 kbps with no termination, the RS-422-compliant receiver reads only the input

differential voltage and produces a clean signal at the output.

Copyright © 2016, Texas Instruments Incorporated

†RT equals the characteristic impedance of the line.

Figure 9-1. Application Diagram

9.2.1 Design Requirements

Resistor and capacitor (if used) termination values are shown for each laboratory experiment, but vary

from system to system. For example, the termination resistor, RT, must be within 20% of the characteristic

impedance, ZO, of the cable and can vary from about 80 Ω to 120 Ω.

9.2.2 Detailed Design Procedure

Add a VCC bypass capacitor (0.1 µF or more). Either enable (G pin) input can turn on the receivers, so connect

the desired enable to a compatible logic line output. The other enable input must be tied to the inactive state

supply rail. If the receivers must always be active, then connect both enables to the supply rail such that at least

one is set to an active-state rail. VCC must be 5 V within 10% and logic inputs must provide TTL-compatible

voltage levels A & B Inputs can lead to an external connector or can be left unconnected. The last receiver

on a cable requires termination, either on-board or use as an external resistor. Unused Y outputs can be left

unconnected.

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AM26LS32AC, AM26LS32AI, AM26LS32AM

AM26LS33AC, AM26LS33AM

SLLS115G – OCTOBER 1980 – REVISED AUGUST 2023

Copyright © 2023 Texas Instruments Incorporated

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