I am interested in designing a BLDC motor driver capable of operating at low supply voltages and relatively high currents (i.e. a device capable of operating with a 3V minimum supply and a phase current > 4A would be ideal). My preference is to use only N-channel MOSFET's, for the usual reasons they're preferred for BLDC motor drivers. To achieve this, I have been investigating half bridge pre-driver IC's. After an exhaustive search (on digikey), I was unable to find any half bridge gate drivers (i.e. both high and low side N-MOS) capable of operating below ~5V (the lowest I've found is the DGD05473, which can operate at 4.5V with an external bootstrap diode).
I am wondering if there is some fundamental reason why these gate drivers have a 5V minimum that I'm missing? Out of thousands of options I expected to see at least a few which could operate at a low supply voltage. If so, does this essentially relegate me to using P-MOS to switch on the high side, or would it be feasible to build out my own discrete high side N-MOS gate drive circuit (inexpensively and in a small form factor).