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Original question:

DRV8873-Q1: nTRIP pull-up and nOL pull-down

DRV8873-Q1: Confused about nOL pullup to nSLEEP

Dmitry Marukh
Prodigy 100 points
Part Number: DRV8873-Q1

The schematic for hardware version (Figure 8) shows nOL pin internally pulled up to nSLEEP.

The description says: "the OLP test is performed at power-up or after exiting sleep mode if the nOL pin is NC or tied to GND", "OLA mode is active when the nOL pin is NC or tied to ground."

Now, if nOL is connected to GND then it will be low all the time, so OLD will be enabled, as expected.

However if nOL is no-connection, it will be pulled high when nSLEEP goes high, so device wakes up with OLD disabled.

So, either nOL is pulled up to nSLEEP, or no-connection means OLD is disabled. Both cannot be true simultaneously.

  • 0
    TI__Guru 54695 points

    Hello,

    What is your desire on the open-load detection behavior?  If you wish to ALWAYS disable it, I suggest you connect it directly to DVDD.  

    It is true that there is an internal pull-up to nSLEEP.  That was not intentional.  There are elements of the design that are shared between the SPI and hardware variants.  The nSCS happens to need a pull-up to the same voltage that supplies the SPI signals.  That is why the pull-up is there.  

    Regards,

    Ryan

  • 0 in reply to Ryan Kehr
    Prodigy 100 points

    Hi Ryan,

    We haven't decided yet if we will use this feature. At this point I am simply trying to find out if the datasheet is incorrect or maybe I do not understand something. Because if there is internal connection to nSLEEP then the statement that NC and GND have the same effect simply cannot be true in my opinion.

  • +1 in reply to Dmitry Marukh
    TI__Guru 54695 points

    Dmitry,

    I would either connect to DVDD (disabled) or GND (enabled).  In my opinion, leaving it floating is not a guaranteed use condition.  

    Regards,

    Ryan