Okay, probably my fault, I should have been more specific.
I need to order from this company if possible (in order to make up a minimum order value), I also like to try to understand what I build, and the components selected (rather than blindly copy someones design). I'm not an electronics engineer, so maybe overlooking some factors, but as far as I can see the requirements for a RAMPS mosfet are:
Vgs < 5v (yes, I know I said 3.3v in my OP, that was copied from something I saw in another post without realising that the logic voltage on the Mega is 5v)
Vds > whatever you plan to switch (plus some overhead)
Id > 50A (less than that gets too hot when using PWM)
Let's forget using this for heatbed or extruders, this will be used in a 7switch design to switch fans, lighting, or similar (comparatively low current devices), but it may need to do PWM. So I can see the FDP7030BL which seems to easily meet those requirements (Vgs 1.9v, Vds 30v, Id 60A), are there any problems with that choice?
One last question, I assume I need to use a voltage divider on the gate input in order to drop the 5v arduino logic level to circa 1.9v (Vgs), from my calculations a 100R and 68R resistor should produce a gate voltage of 2.02v (close enough). The reason I question this is the SevenSwitch schematic shows values of 10R and 1M (which doesn't really divide the voltage at all), so what am I missing?
I need to order from this company if possible (in order to make up a minimum order value), I also like to try to understand what I build, and the components selected (rather than blindly copy someones design). I'm not an electronics engineer, so maybe overlooking some factors, but as far as I can see the requirements for a RAMPS mosfet are:
Vgs < 5v (yes, I know I said 3.3v in my OP, that was copied from something I saw in another post without realising that the logic voltage on the Mega is 5v)
Vds > whatever you plan to switch (plus some overhead)
Id > 50A (less than that gets too hot when using PWM)
Let's forget using this for heatbed or extruders, this will be used in a 7switch design to switch fans, lighting, or similar (comparatively low current devices), but it may need to do PWM. So I can see the FDP7030BL which seems to easily meet those requirements (Vgs 1.9v, Vds 30v, Id 60A), are there any problems with that choice?
One last question, I assume I need to use a voltage divider on the gate input in order to drop the 5v arduino logic level to circa 1.9v (Vgs), from my calculations a 100R and 68R resistor should produce a gate voltage of 2.02v (close enough). The reason I question this is the SevenSwitch schematic shows values of 10R and 1M (which doesn't really divide the voltage at all), so what am I missing?