Is there any way to run the NexFET power stages at 100% duty cycle? One option that I am considering is to apply a higher voltage to the Boot pin instead of using the boot cap. For the sake of simplicity, assume I am switching with Vdd = 5V, Vin = 4V, and that I have a 9V supply available on the board -- can I apply this directly to the boot pin?
Part of my confusion stems from the fact that the datasheet states that the absolute maximum rating of BOOT to BOOT_R can only be Vdd+0.3. In the scenario that I outlined above, the BOOT to BOOT_R voltage would be 9V when the lower FET is turned on, which would exceed this rating. However, the part is rated to have a Vin of up to 16V. If were using it in this configuration (with the standard boot cap instead of my alternative power supply), the BOOT and BOOT_R pins would be as high as 21 and 16V respectively, but the chip would be operating in a safe zone.
Is there a diode not shown in the functional block diagram?