All LDOs are integrated so that they can be connected to a system supply, to an external buck boost SMPS, or to another preregulated voltage source. The output voltages of all LDOs can be selected, regardless of the LDO input voltage level VI. There is no hardware protection to prevent software from selecting an improper output voltage if the VI minimum level is lower than TDCOV (total DC output voltage) + DV (dropout voltage). In such conditions, the output voltage would be lower and nearly equal to the input supply. The regulator output voltage cannot be modified on the fly from one (0.9–2.1 V) voltage range to the other (2.2–3.3 V) voltage range and vice versa. The regulator must be restarted in these cases. If an LDO is not needed, the external components can be unplaced. The TPS65903x-Q1 devices are not damaged by such configuration, and the other functions do not depend on the unused LDOs and work properly.