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DS26F32MQML: 5962-7802005M2A

ANIKET SHUKLA
Prodigy 155 points
Part Number: DS26F32MQML

We have been using IC 5962-7802005M2A (DS26F32ME) from TI in our design for RS422 line receiver. The datasheet states that the IC has a fail-safe I/O relation. Kindly request you to confirm the same. Datasheet is attached for reference.

Also during testing it is observed that we are receiving junk data when pull-ups and pull-down resistors are not connected at input of IC. Kindly request you to confirm whether it is mandatory to use pull-ups and pull-down resistors? The same circuit works without pull-ups and pull-down when alternate (form-fit-function) IC 5962-7802001M2A (26LS32M) is used (as provided in MIL datasheet 5962-78020). Kindly clarify the same at the earliest.

  • 0
    TI__Guru 62930 points

    Aniket,

    The datasheet implies a pull down on on the differential input pins.  Unfortunately, there is very little other information.

    I need to do some research and see if I can locate some input schematics or other information that may help clarify this.

    Can you provide your input biasing and termination?   This may be important to the analysis.  Do you have 2 schematics?  One with input biasing, and one without?

    Regards,

    Wade

  • 0 in reply to Wade Vonbergen
    Prodigy 155 points

    We would like to know whether there is any internal up as the fail safe operation holds the pins high? If so what is the value of internal pull used?

    Please consider the delay in processing your clarification. Please find attached the required schematics. The IC is used without pull up and pull down resistors and we are getting random junk data. Kindly confirm whether the pull ups/down are required/ mandatory for faithful application. Although the similar MIL grade IC 5962-7802001M2A works fine without pull-ups/down.

  • 0 in reply to Wade Vonbergen
    Prodigy 155 points

    We would like to know whether there is any internal up as the fail safe operation holds the pins high? If so what is the value of internal pull used?

    Please consider the delay in processing your clarification. Please find attached the required schematics. The IC is used without pull up and pull down resistors and we are getting random junk data. Kindly confirm whether the pull ups/down are required/ mandatory for faithful application. Although the similar MIL grade IC 5962-7802001M2A works fine without pull-ups/down.

  • 0 in reply to ANIKET SHUKLA
    TI__Guru 62930 points

    Thanks for the schematic.

    I am still searching for input schematics.  Unfortunately, they may not be available any longer.

    What external biasing were you using to get it to work correctly?

    Can you provide some scope shots of the inputs?  When not using external failsafe biasing.

    When you are getting junk data, is buss floating, and you expect failsafe low?   Please provide scope shot of capture of bad data.

    Regards,

    Wade

  • 0 in reply to Wade Vonbergen
    TI__Guru 62930 points

    Aniket,

    I was able to locate input equivalent schematics.

    Both inputs have 3.2K pullups to VCC, and IN- has a very small pull down to ground to create small VID.  This will create a logic 0 output when both pins are floating.

    This input structure is not intended to be a failsafe implementation, but appears to handle floating, open, or unused inputs.  This is what the features bullet on the first page indicates.

    Proper failsafe operation will require external biasing.

    If this answers your question, please click "This Resolved My Issue"
    Regards,
    Wade