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system configuration Attached is the current lab setup for my chip testing. The green square represents the main PCB board, and little blue square represents the chip. The chip needs separate VDD voltage for its analog and digital circuits, but their ground is tied on the green PCB.

From here, I am seeking advice regarding the possible concerns about ground loop if '-' terminal of PSU is connected to the earth ground in the given situation.

I did some research on this matter and discovered that there are pros and cons to connecting the negative terminal of PSU to earth GND. On the one hand, shorting the '-' terminal of the PSU to earth ground can reduce common-mode noise caused by the parasitic cap b/w local GND and earth GND, but on the other hand, it may create a ground loop, which can possibly pick up 60Hz interferences.

Initially, I was of the opinion that connecting the '-' terminal to earth GND in my situation would not be advisable since the neutral pin for the PC power adapter is connected to earth GND, and this would create a GND loop if the PSU '-' terminal is shorted to the earth ground. However, other senior students in my lab have suggested that the PSU '-' terminal should always be connected to the earth GND unless a negative supply voltage is required. any feedback would be greatly appreciated.

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    \$\begingroup\$ Data sheet links on the two power supplies are probably needed. Try formatting your words so that it isn't a wall of text. What else in your system might be earthed? NB in the UK when we refer to earth we mean a connection to an earth rod buried in the soil. If we say ground, we don't usually mean earth so, bear that in mind should any answers come along. In the US, ground can mean earth but, this doesn't imply that all grounds are earthed. \$\endgroup\$
    – Andy aka
    Commented May 10, 2023 at 11:34

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The PC is already earthed/grounded to mains PE wiring as you are using a 3-prong plug.

If it is a standard desktop PC, the PE earth/ground is already connected to PC metal chassis and to the common circuit ground inside the power supply.

The green terminal on lab power supply is also connected to mains PE via mains plug and lab supply voltage red and black output terminals are floating in respect to the green PE terminal.

In this case it would be best to not connect lab supply green terminals anywhere. The PCB is already earth-grounded through the PC.

If you connect the lab supply green terminal to PCB or to lab supply black terminal, that will create a DC path for a ground loop, through mains PE wiring inside the mains distribution network (either on your desk if devices are connected to same power strip, or via mains wiring inside walls).

And if you disconnect the lab supply black wire while black terminal is connected to green terminal, your device will be powered as the return path is via mains PE wiring of the power strip or room.

That's enough of a reason to prefer not using the green PE terminal on a lab PSU.

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