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AM26C31: Absolute Maximum Ratings of AM26C31 / AM26LS31 Output Pins

Conor
Guru 10880 points
Part Number: AM26C31
Other Parts Discussed in Thread: AM26LS31

Tool/software:

Hi,

We are investigating the differences between AM26C31 and AM26LS31 and would like to confirm the following points regarding their output pin absolute maximum ratings.

  1. Do the AM26C31 and AM26LS31 output pins have the same absolute maximum ratings?

    • The datasheets specify the same value (7V), but we would like to confirm whether they have the same tolerance levels.

  2. Does the 7V rating also apply to externally applied voltages?

    • The datasheets do not clearly specify whether the 7V rating refers to the "operating range of the internal circuitry" or the "maximum externally applicable voltage."

We appreciate your clarification on these points.

Best regards,
Conor

  • +1
    Guru 301490 points

    The absolute maximum ratings are different (the LS supports only 5.5 V). Anyway, it matters only when the device is disabled or powered off; when the driver is active, it drives the bus to a voltage between GND and VCC, and you would have to apply a very strong external signal to force the output voltage to a different value. (Both devices specify a short-circuit current of up to 150 mA, and that current is not allowed for a long time.)

  • +1
    TI__Guru 64470 points
    Conor said:

    Do the AM26C31 and AM26LS31 output pins have the same absolute maximum ratings?

    • The datasheets specify the same value (7V), but we would like to confirm whether they have the same tolerance levels.

    As Clemens pointed out, the LS has an extra condition where if the device is unpowered it can only handle up to 5.5V

    Conor said:

    Does the 7V rating also apply to externally applied voltages?

    • The datasheets do not clearly specify whether the 7V rating refers to the "operating range of the internal circuitry" or the "maximum externally applicable voltage."

    These are in reference to the external pins. Applying an external voltage larger than 7V on an input pin for example would break the device (if pin voltage reference to its GND > 7V in reference to the same GND). 

    -Bobby