Antonio Zanardo wrote:I wonder if I can stack two mosfets of that type by paralleling them pin to pin, and if the twin ones behave just like one. Should I expect from the mosfet pair double current, half on resistance, double input capacitance?
The stock controller has only 6 mosfets, so I would arrange the new 12 mosfets on two 6 unit strings placed on a separate board.
Each string would have its buss bars interconnected to the other string in order to paralleling mosfets, and each string would have its proper heat sink.....
What should I expect from this arrangement? I would be happy if the on resistance of the coupled mosfets is cut in half, but worried if the input capacitance gets twice as much!
Any comment/suggestion will be greatly appreciated.
Yes, you can parallel the FETs as long as each one has its own gate resistor. Do not put the gates in parallel directly. The gate resistors should be at least 10 ohms.
The gate capacitance could be an issue depending on the drivers, but based on our combined experience here, you can increase the capacitance quite a bit without causing switching speed problems.
Doubling the FETs will cut the on resistance in half. As long as the switching speed stays fast, the heating will be about half as well. I think current spikes are responsible for most failures, so with twice the current capacity, reliability should be improved.
Go for it!