I’m new to this forum and currently working on a Anti-spark switch for my boards.
All the available projects didn’t fit my needs, so I decided to design my own switch. In my opinion, they all were too big, or too expensive or didn’t have the feature I needed.
It has the following features:
- dimensions: 74mm x 38mm
- theoretically Rdson of 90 uOhm
- maximum current of around 200A (more with additional copper and cooling)
- maximum voltage of 60V
- 12V 50mA LDO output
- controlled dI/dt with capacitor and current limiting resistor
- two IRFS7530 N-channel MOSFET
- BQ76200PWR High Side MOSFET Driver
- A holder for a LittleFuse BF1
- 4 pin JST XH connector for an external switch
- exposed pcb traces to add solder or a copper bar for lower resistance
The 12V LDO is only used to drive an LED that is included in my switch. It won’t deliver much current, due to the high heat dissipation: 38V delta voltage means 0.38W for every 10mA, which is much for such a small package. You can leave it unused if you want.
As seen by other Anti-Spark switches I went with the LittleFuse BF1. It can be soldered directly to the PCB, so there is no need of screw terminals. However, there are 6.5 mm screw holes. You can also use a copper strip in replacement for the fuse.
The MOSFET are connected to the Driver over an RC element to slowly turn on the MOSFET in order to have controlled dI/dt for high capacitive loads.
If you order the PCB on JLCPCB ( 1.8€ for 5 pcs) and the parts from mouser, it will only cost around 30€ (you can use fewer MOSFET to decrease the prize). The SMD components can be soldered with a little bit of skill and a standard soldering iron.
exposed PCB traces
The PCB traces for the power lines are exposed so that a copper bar or additional solder can be attached to it, to decrease the resistance. like this copper bar
The project is available on GitHub under this link
I will improve and finalize the PCB in the next days and order some at JLCPCB in the next days and see if everything is working as expected. Especially if the PCB can handle the current.
I’ll get back to you as soon as I know the details.
If you have any suggestion or question, feel free to comment!