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Original question:

LMH6881: WQFN package questions about packaging (leads and resin molds) follow-up

DS92LV2411: w/ pull-down meaning in the datasheet

FRANK1
Expert 8105 points
Part Number: DS92LV2411
Other Parts Discussed in Thread: DS92LV2412

Hi Team,

I want to consult the pin function of DS92LV2411.
There is a pin function table on page 3 of the data table for DS92LV2411.
There is an item of "type" on the table, which says w / pull-down.
I can't find the description here in the datasheet.
Please tell me what it means.
Please tell me the following Q1 ~ Q4

Q1 What does "w /" mean?

Q2 "pull-down" refers to the built-in pull-down terminal? right?

Q3 What is the pull-down resistance value with built-in pull-down? (there is no specification in the data sheet)

Q4 the description of 8.3.2.10 DES-Strap Input pins of DS92LV2412 in the same data table is as follows:

" open (NC) for Low, no pull-down is required (internal pull-down)"
Similarly, when setting the low of the strap input pins with w / pull-down, it says that there is no need for external pull-down resistance.

However, with regard to the terminal of DS92LV2411, the necessity of external pull-down resistance is not specially recorded.
If w / pull-down like config pin is written on the terminal of DS92LV2411, set low on the input terminal.
Does it need an external pull-down resistor?

Or is there no problem with open like strap input pins?

Thanks for your clarification.

Regards,

  • 0
    TI__Guru** 103215 points

    Hello Frank,

    Today is a US holiday so we will back back in office tomorrow 1-18-22. Thank you for your patience during this time 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    TI__Expert 8105 points

    Hi Casey,

    Okay, waiting your feedback.

    Thanks.

  • +1 in reply to FRANK1
    TI__Guru** 103215 points

    Hello Frank,

    FRANK1 said:
    Q1 What does "w /" mean?

    This means "with pulldown"

    FRANK1 said:
    Q2 "pull-down" refers to the built-in pull-down terminal? right?

    Yes this means internally the pin has a pulldown to GND

    FRANK1 said:
    Q3 What is the pull-down resistance value with built-in pull-down? (there is no specification in the data sheet)

    Will need to check on this internally and see if we have data. This is a legacy device so it may take several weeks to make a check to see if we can specify the typical pulldown resistance 

    FRANK1 said:

    Q4 the description of 8.3.2.10 DES-Strap Input pins of DS92LV2412 in the same data table is as follows:

    " open (NC) for Low, no pull-down is required (internal pull-down)"
    Similarly, when setting the low of the strap input pins with w / pull-down, it says that there is no need for external pull-down resistance.

    However, with regard to the terminal of DS92LV2411, the necessity of external pull-down resistance is not specially recorded.
    If w / pull-down like config pin is written on the terminal of DS92LV2411, set low on the input terminal.
    Does it need an external pull-down resistor?

    Or is there no problem with open like strap input pins?

    This is more of a system level question. In general, for pins like this with internal pulldown the resistance is usually relatively high meaning that the pin is weakly pulled down. In a low noise environment this means that the pins would not need an external pulldown to set a low level, but generally it is a good best practice to include external pulldowns at least as a placeholder to ensure noise does not pull the pin high unexpectedly in the total system environment 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    TI__Expert 8105 points
    Casey McCrea said:
    ronment 

    Hi Casey,

    Thank you for your response.

    Well noted.

    For Q3 pull-down resistance value, please tell me once you get it.

    waiting your update.

    Thanks,

  • 0 in reply to FRANK1
    TI__Guru** 103215 points

    Hello Frank,

    In checking for data on the pulldown we are not able to find any clear indication of the pulldown resistance range and this device is quite an old legacy part at this point so it doesn't seem likely we will be able to obtain this info. I would advise that the customer at least leave stuffing options in their design for optional pulldown resistors on the strap pins if they are worried about noise coupling in and pulling the pins high. They could choose not to populate the resistors after doing their system level validation and confirming no issues 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    TI__Expert 8105 points

    Hi Casey,

    Thank you.

    Got it.