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DRV8313: Risks when PGND is not connected to GND

Hao Wang14
Expert 4415 points
Part Number: DRV8313

Hi Team,

PGND is recommended to connect with GND when there is no Rsense. I have two questions, could you please hep explain? Thanks!

1. What are the risks when PGND is not connected to GND? Because several pieces are damaged when doing so by accident.

2. What's the internal connection between PGND and GND? Because the measured resistance between PGND and GND is 3 ohms with DRV8313 only, it seems that PGND and GND is connected internally, why is it designed like this?

Best Regards!

Hao

  • 0
    TI__Guru 65390 points

    Hao,

    Thanks for posting on the MD forum!

    1. I am assuming the damage occurred when the PGND was not connected to GND on the PCB. The reason for the damage is likely that the GND to PGND connection on the board is required. Internally there is some connection between GND and PGND but it is not intended to carry the amount of GND current needed in a design such as this. Some internal node was likely damaged because it needed to carry the current which is usually handled by the PCB GND to PGND connection.
    2. There are several connections internal to the device between PGND and GND. The power supplies and device protection circuits both use GND and PGND for example. The reason you are seeing 3 ohm is because not all the connections between PGND and GND are shorts, some connections are diodes and other internal components. We cannot internally short GND and PGND because this would remove some flexibility for customers to use Rsense as needed. We rely on the PCB connection from PGND to GND to carry the required current between the two nodes.

    Regards,

    -Adam