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DRV8886: DRV8886 Ground Isolation

user5981129
Prodigy 30 points
Part Number: DRV8886

Hello,

I can see in the DRV8886 datasheet two grounds (GND and PGND). As far as I can see PGND is the lower voltage of the H-Bridge but I still have the following doubts:

- Could I connect GND and PGND to separate grounds in my board? (grounds in my board are connected in only one point) I mean, Are GND and PGND isolated inside the driver?

-Which signals are referenced to each ground? (AVDD, DVDD, step, etc...)

Measuring the resistance between GND and PGND I can measure a DC resistance of 628 Ohms aprox., and that lead me to think that a kind of isolation exists between those pins.

Thanks in advance.

J.R.

  • 0
    TI__Guru 56650 points

    Hello,

    From the pin function table, you can see GND is the device ground. So, all AVDD, DVDD, Srep, etc... are reference to it.

    PGND is the power ground. A high current path can go through it.

    Both GND and PGND are connected to system ground. We don't want to make the system ground too far away from motor drive circuit to avoid a big voltage difference between GND and PGND.

  • 0 in reply to Wang5577
    Prodigy 30 points
    Hello Wang Li,

    I'll try to explain my question in other words.
    By one hand I want to separate the grounds and just connect them in one point on my board to avoid noise from the H-Bridge, providing good returns for each signals without mixing them.
    By the other hand, if the device grounds are internally connected, ground loops and undesirable returns could arise as a result of grounds connected in several points.
    Thus my question is about the construction of the DRV8886 and to know is the two device gounds are internally connected or isolated in order to avoid the previous problems.

    Thanks again
    J.R.
  • 0 in reply to user5981129
    TI__Guru 56650 points
    J.R,

    As your measurement result, the two DRV8886 ground are not short together directly. It could have a diode between them. So, please don't have two ground voltage difference higher than a diode.