I have been looking at this issue for a while and I would like to get feedback from the more knowledgeable members.
I have a PCB with a few FET drivers ( amongts other things) driving a number of external solenoids/valves. (see attached pdf file). The file just show a generic high side driver drawing so you will get the idea. The L would be one of the solenoids and for simplicity sake I just put one of them there.
D1 is placed in the PCB and the solenoids are located somewhere else, with the ground to them wired directly rather than through the board.
Power and GND for the board are wired as shown. This arrangement is pretty standard and worked fine for years and still works.
However, here is the fun fact. If the GND wire to the PCB breaks or the connection fails in any way, then the main ground path will be open. When this happens the actual flyback diode will provide a path to ground through the solenoid and back to the solenoid ground. As a result the ground in the PCB now is floating with respect to the main ground and whenever any of the solenoids is activated the ground voltage spikes just go through the roof, eventually killing either the switching power supply or the controller.
I have tried to battle this problem, which is not huge, but just bothers me, using TVS and other concoctions, but little results, so have anybody seen/faced/solved this issue before?
Thanks
I have a PCB with a few FET drivers ( amongts other things) driving a number of external solenoids/valves. (see attached pdf file). The file just show a generic high side driver drawing so you will get the idea. The L would be one of the solenoids and for simplicity sake I just put one of them there.
D1 is placed in the PCB and the solenoids are located somewhere else, with the ground to them wired directly rather than through the board.
Power and GND for the board are wired as shown. This arrangement is pretty standard and worked fine for years and still works.
However, here is the fun fact. If the GND wire to the PCB breaks or the connection fails in any way, then the main ground path will be open. When this happens the actual flyback diode will provide a path to ground through the solenoid and back to the solenoid ground. As a result the ground in the PCB now is floating with respect to the main ground and whenever any of the solenoids is activated the ground voltage spikes just go through the roof, eventually killing either the switching power supply or the controller.
I have tried to battle this problem, which is not huge, but just bothers me, using TVS and other concoctions, but little results, so have anybody seen/faced/solved this issue before?
Thanks
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