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I have a hat board that has some high power solid state switches (mosfets). The hat is controlled by the main board. The hat and the main board are connected via pin headers, like an arduino. Th...
#3: Post edited
by
DeadMouse
·
2024-11-30T10:56:12Z (18 days ago)
- I have a hat board that has some high power solid state switches (mosfets).
- The hat is controlled by the main board.
- The hat and the main board are connected via pin headers, like an arduino.
- The hat board contains some connectors for the power and also the outputs.
- My main concern is how to avoid high current flowing back and down to the main board in case the ground disconnects from the hat board.
- A schematic below:
- 
- Blue box represents the high power part of the hat board and the rest is the control circuit.
- `SW2` represents the external ground wire of the output connector the hat board.
- In theory, if the wire cuts off, `SW2` opens. No current will flow back to the control circuits due to high resistance of `R3`.
- I could also leave `R3` unconnected but I Don't know how the circuit will behave with a floating source pin.
- I can't have an isolated supply for 3.3V (`V2`). As the main board exists already. The main board contains a DC/DC that steps down 24V to 3.3V.
There will be two power lines. One for the main board, its operation. And one for the top board, the high power part. Those two are exactly the same source.
- I have a hat board that has some high power solid state switches (mosfets).
- The hat is controlled by the main board.
- The hat and the main board are connected via pin headers, like an arduino.
- The hat board contains some connectors for the power and also the outputs.
- My main concern is how to avoid high current flowing back and down to the main board in case the ground disconnects from the hat board.
- A schematic below:
- 
- Blue box represents the high power part of the hat board and the rest is the control circuit.
- `SW2` represents the external ground wire of the output connector the hat board.
- In theory, if the wire cuts off, `SW2` opens. No current will flow back to the control circuits due to high resistance of `R3`.
- I could also leave `R3` unconnected but I Don't know how the circuit will behave with a floating source pin.
- I can't have an isolated supply for 3.3V (`V2`). As the main board exists already. The main board contains a DC/DC that steps down 24V to 3.3V.
- There will be two power lines. One for the main board, its operation (steps down to 3.3V). And one for the top board, the high power part. Those two are exactly the same source.
#2: Post edited
by
DeadMouse
·
2024-11-30T10:48:06Z (18 days ago)
- I have a hat board that has some high power solid state switches (mosfets).
- The hat is controlled by the main board.
- The hat and the main board are connected via pin headers, like an arduino.
- The hat board contains some connectors for the power and also the outputs.
- My main concern is how to avoid high current flowing back and down to the main board in case the ground disconnects from the hat board.
- A schematic below:
- 
- Blue box represents the high power part of the hat board and the rest is the control circuit.
- `SW2` represents the external ground wire of the output connector the hat board.
- In theory, if the wire cuts off, `SW2` opens. No current will flow back to the control circuits due to high resistance of `R3`.
I could also leave `R3` unconnected but I Don't know how the circuit will behave with a floating source pin.
- I have a hat board that has some high power solid state switches (mosfets).
- The hat is controlled by the main board.
- The hat and the main board are connected via pin headers, like an arduino.
- The hat board contains some connectors for the power and also the outputs.
- My main concern is how to avoid high current flowing back and down to the main board in case the ground disconnects from the hat board.
- A schematic below:
- 
- Blue box represents the high power part of the hat board and the rest is the control circuit.
- `SW2` represents the external ground wire of the output connector the hat board.
- In theory, if the wire cuts off, `SW2` opens. No current will flow back to the control circuits due to high resistance of `R3`.
- I could also leave `R3` unconnected but I Don't know how the circuit will behave with a floating source pin.
- I can't have an isolated supply for 3.3V (`V2`). As the main board exists already. The main board contains a DC/DC that steps down 24V to 3.3V.
- There will be two power lines. One for the main board, its operation. And one for the top board, the high power part. Those two are exactly the same source.
#1: Initial revision
by
DeadMouse
·
2024-11-29T07:45:11Z (19 days ago)
Ground loss protection
I have a hat board that has some high power solid state switches (mosfets). The hat is controlled by the main board. The hat and the main board are connected via pin headers, like an arduino. The hat board contains some connectors for the power and also the outputs. My main concern is how to avoid high current flowing back and down to the main board in case the ground disconnects from the hat board. A schematic below:  Blue box represents the high power part of the hat board and the rest is the control circuit. `SW2` represents the external ground wire of the output connector the hat board. In theory, if the wire cuts off, `SW2` opens. No current will flow back to the control circuits due to high resistance of `R3`. I could also leave `R3` unconnected but I Don't know how the circuit will behave with a floating source pin.