If you look at "Fig 12. On-Resistance vs. Gate Voltage" you will see why IRLB8743PBF is not suitable for 3.3V use. It needs a 5V gate driver as STB asserts. That also solves the gate capacitance problem. It is also why they state the max RDSon at 4.5V. You can design it into a 5V system and have some margin for the 5V rail being 5% low and some drop in the logic gate and still have a guaranteed RDSon figure.
I don't know if there are any MOSFETs that are fully enhanced at 3V. When switching just a few amps they can work fine but once you get into tens of amps I think a gate driver is always needed. It costs pennies and means you generate less heat, which makes the PCB design easier. Or it means you can use a cheaper MOSFET with higher RDSon and get an overall lower cost.
I usually include a small series resistor reduce the chance of parasitic oscillation and control the edge speed to meet EMC specs. There is no point in having very fast switching edges driving the bed when it takes seconds to respond. All it does is ring at the resonant frequency of the wiring, which will be in the VHF band. Since we are switching about 100W that can be a massive RF source.
I don't know if there are any MOSFETs that are fully enhanced at 3V. When switching just a few amps they can work fine but once you get into tens of amps I think a gate driver is always needed. It costs pennies and means you generate less heat, which makes the PCB design easier. Or it means you can use a cheaper MOSFET with higher RDSon and get an overall lower cost.
I usually include a small series resistor reduce the chance of parasitic oscillation and control the edge speed to meet EMC specs. There is no point in having very fast switching edges driving the bed when it takes seconds to respond. All it does is ring at the resonant frequency of the wiring, which will be in the VHF band. Since we are switching about 100W that can be a massive RF source.