I am using an Allegro Microsystems A4935 3-phase MOSFET driver in a brushless speed controller. I recently got the motor spinning, but when I began increasing the voltage, my commutation started to become jerky, for reasons I suspect to be in software.
What I'm confused about is that, when this happens, both my MOSFETs and MOSFET driver heat up. At one point I released the magic smoke in the driver, and eventually the VBB trace (high voltage, supply for gate driver circuitry) going into the MOSFET driver even burned and broke! I understand that whenever the motor gets stuck, it causes large amounts of current through the MOSFETs, but why does this cause the MOSFET driver to heat up also?
The resistors I have at the gates of my IRFS7530 MOSFETs are 4.7Ω, and I'm driving the PWM at 25kHz. The driver only gets a little warm at no load driving the capacitance of the MOSFETs. My question is, what causes this stress on the driver when there is a load? Why does sudden high current flowing through the MOSFETs cause the MOSFET driver to need lots of current? Isn't the only load on the driver due to charging the gates, which is independent of the current through the MOSFETs?
Here is the schematic for the relevant part of the circuit: