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TIDA-00366: Grounding scheme

JIGNESH PATEL
Prodigy 10 points
Part Number: TIDA-00366


Tool/software:

Hi,

In TIDA-00366 reference design, the grounding scheme is such that the reference points (U_BOT_REF, V_BOT_REF, and W_BOT_REF) are connected together to VDC- through 0-Ω resistors R133, R139, and R140 respectively. They are also connected with the GND1 (ground for a 16-V gate-drive power supply) through one more 0-Ω resistor R142.

It implies that each of the bottom side Gate driver Gnd is connected to Gate driver Power supply Gnd and to VDC- thorugh the 0ohm shorting links on the PCB.

I have couple of questions on this arrangement

  1. What is the use of this shorting link? Why not directly connect all the bottom side 3-Ph gate driver section Gnd through some common star point in the layout routing itself?
  2.  Which is a better grounding scheme in case of external Power modules with external AC and DC busbar arrangement

a) Connecting all the bottom side grounds of Gate driver section together through shorting links/layout in PCB 

OR

b) Keeping the Gnd Plane of all the bottom side Gnd separate on PCB as they ultimately get connected through the VDC- busbars?

3. In continuation to question 2, what if individual power supplies were given to bottom side gate drivers. Do we need to connect its Gnd together on PCB or tie it at one end on PCB OR should we keep the ground plane of each of the bottom side gate driver phase separate and then it gets connected externally through VDC- busbars?

  • 0
    TI__Intellectual 1620 points

    Hi Jigesh,

    Thank you for reaching out to us on these questions.

    1. As you have mentioned, GND1 is the control side GND; and VDC- is the power side GND. This design has been trying to divide these two and only connect them at the 0-Ω resistor R142. This has been the main purpose. This may not be the best or a perfect pattern. You can try with the star pattern and others for comparison.

    2. If we can devide the power GND and the control GND, then the (a) pattern seems better. After all, we need to connect them together at the shared low-side 16V control supply. For (b) pattern, if we can use three 16V control supplies for each low-side gate drive, as you mentioned in question 3,  it would be better. Otherwise it may form many loops between the channels as the GND have to be connected at both the power side and the control supply side. In this case, a GND plane to reduce the impedance within and between the channels' low-side circuit, or the (a) pattern, may be better.

    Best regards,

    Jerome Shan