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TIDM-02010: The issue of hardware GND and PGND isolation

Yu Lee
Prodigy 50 points
Part Number: TIDM-02010


In the design scheme TIDM02010A of TI's 1.5kw compressor, I noticed that the power ground PGND was not completely isolated from the signal ground GND. However, the power supply design scheme already used a flyback power supply, which is a power supply with isolation function.

The schematic and PCB both show that these two grounds are connected by a piece of copper. Shown as the belowing pictures, and my question is, can I remove this copper, to make the PGND and GND are totally isolated?

image.png

image.png

  • 0
    TI__Mastermind 27745 points

    已经收到了您的案例，调查需要些时间，感谢您的耐心等待。

  • +1 回复 Eirwen
    TI__Mastermind 27745 points

    This is non-isolated design. Function of flyback is just step down the 400V bus to various rails 15V/12V/5V etc not the isolation.

    You need these two connected otherwise all sensing signals, GPIOs and PWMs won't have same reference.

    If you isolate these two ground then you need to use isolators for all above signal as well. Considering this is appliance design which is cost sensitive, isolators will increase the cost.

    In nutshell, No you can't separate these gnds.

  • 0 回复 Eirwen
    Prodigy 50 points

    Yes, you are right , thanks again. I have noticed these problems later, the sensor signals based different GND, and if PGND and GND is isolated, the current feedback and PFC Vdc sampling signals will be wrong.