TAS5111A - Why does this device require a power on and power off sequence?

This device does not contain a power on reset circuit; therefore, you must apply GVDD (the supply voltage for the gate drive) to get control of the output H-Bridge before you apply the H-Bridge power supply (PVDD) or device damage can result.

Newer devices like the TAS5142, TAS5352, etc, have an internal power on reset circuit and do not have this requirement.