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AM26LS32AC: Converts the differential signal to a different logic state or not

Danilo A.
Mastermind 28660 points
Part Number: AM26LS32AC

Hi Team,

Table 1 of Section 8.4 Device Functional Modes shows the output Y of AM26LS32AC when VIT– ≤ VID ≤ VIT+ is indeterminate. A customer would like to know whether the device converts the differential signal to a different logic state or not.

Regards,

Danilo

  • 0
    TI__Guru 53555 points

    Hi Danilo,

    The differential line receiver is designed to receive a differential signal on its A and B pins and output a corresponding digital state on its Y pins. The logic for this operation is shown on Table 1 - if the voltage at the A terminal is greater than the voltage at the B terminal by the positive going input threshold, the output of the corresponding receiver will be high (vA - vB >= vIT+ : Y = H). If the voltage at the A terminal is less than the voltage at the B terminal by the negative going input threshold, the output of the corresponding receiver will be low (vA - vB >= vIT- : Y = L). While the difference between the differential signals A and B is between these two thresholds, the output Y is indeterminate because neither of these conditions is met. However, many modern RS-485 transceivers, including AM26LS32AC, include a fail-safe feature which keeps the outputs in a known state when the inputs are open. In practice, this means that when the difference of voltage between A and B is very small, the output Y will remain high. 

    Please let me know if this answers your questions or if there's anything else I can clarify. 

    Regards,
    Eric Schott