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DRV8323: analogue and digital grounds issue

Cherry Zhou
Mastermind 22235 points
Part Number: DRV8323

Hi team,

Here's an issue from the customer may need your help:

Is it essential to distinguish between analogue and digital grounds? Is it OK to use only one GND? Here're 2 ways as below:

1) Only one GND, no agnd and pgnd. Is it affecting sampling?

2) With the analogue and protective grounds,  the schematic is as follows:

Does it have a significant impact on the results without distinguishing between digital and analogue? Both GND and AGND, 3.3 V and AVCC are connected through a 0 ohm resistor. 

Could you help check this case? Thanks.

Best Regards,

Cherry

  • 0
    TI__Prodigy 620 points

    Hi Cherry!

    Let me consult with the team and I will get back to you!

    Tyler McCulloch

  • 0 in reply to Tyler McCulloch
    TI__Prodigy 620 points

    Hi Cherry,

    From a parasitic capacitive and inductive perspective, common ground is much better than split ground. Split GND is only ever used to divert high-frequency current as well as large amounts of current away from sensitive components. Common ground is generally better for heat dissipation as well, since the copper pour on the PCB will not be split into sections. Common GND is much easier to implement in PCB design, saving both time and money during the development process.

    If high-frequency current is a concern or if large amounts of current will be present near the sensitive components, then split GND should be considered. However, this will add inductance to these new split ground paths. It is generally more expensive and challenging from a design perspective to implement a split ground.

    Unfortunately, this means there is no one answer. It all depends on the application. Based on the selection of DRV8323 (gate driver) it seems like there will most likely be higher currents present in the system. The customer needs to consider what switching frequencies will be present in their design, what their expected motor drive currents will be, etc. Overall, we would recommend a common GND to save on cost and complexity.

    Feel free to reach back out to me if they want a specific answer based on their application. 

    Let me know if this resolves your issue!

    Tyler McCulloch