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LMG5200EVM-02: Isolation between PGND and AGND

Maximilian Lemke
Prodigy 10 points
Part Number: LMG5200EVM-02
Other Parts Discussed in Thread: LMG5200

Tool/software:

Hello,

I have a question about the different ground potentials of the Evaluation Board. As I see from the schematic, GND and PGND should not be connected anymore if I desolder R10. The Half-Bridge Power Stage (LM5200) can be used for isolated applications.

However, after desoldering R10, I still measure a connection (short) between GND and PGND without anything connected to the Evaluation Board. The board has not been used before. Do I need to disconnect other components from the board so that GND and PGND are no longer connected?

Best regards,

Max

  • +1
    TI__Expert 7415 points

    Hi Max,

    The AGND and PGND pins are electrically connected inside the device, therefore there will always be a short between these nets. The R10 net tie is useful when doing debugging when the LMG5200 is not installed on the board and a connection is still needed between these two grounds.

    Thanks,

    John

  • 0
    TI__Expert 4520 points

    Hello,

    Follow-up to John's point:

    AGND and PGND are separated on the device to prevent noise from high current PGND loop from entering LI and HI digital signal paths. However, AGND and PGND must be connected together externally with a kelvin connection because the digital signals are still referenced to the same ground as the power FETs. Disconnecting AGND and PGND would cause device to not operate as expected. The device is designed to be used in isolated topologies but the device itself is all referenced to the same ground.

    Thanks,
    Zach 

  • 0 in reply to John Gomez
    Prodigy 10 points

    Thank you for your reply. This solved my issue.

    Best regards,

    Max