Note: TIDM-1003 is TI design "Low-Voltage 50-A Sensorless FOC for BLDC or PMSM ref design" - this posting window does not recognize this entered number, probably because it is new design.
What is the current output requirements for each DC-DC converter in this design:12v, 5, 3.3v ? Assuming that converters are not chained but all convert from Vdc input range. If they are chained as in this design - each stage should in addition produce current needed for all down stages. Key system specification does not mention requirements even for the external feed Vdc.
Also related: What is the benefit of making a chain: each converter is a step-down buck of the previous ? 12v converter has to have enough power to also include current for the lower converters - probably more power dissipation (even though step-down voltage differences are lower)?