JAJSU80 March 2024
ADVANCE INFORMATION
This section describes power sequence requirements using power sequence diagrams and associated notes. Each power sequence diagram demonstrates the sequential order expected for each device power rail. This is done by assigning each device power rail to one or more waveform. A dual-voltage power rail may be associated with more than one waveform and the associated note will describe which waveform is applicable. Each waveform defines a transition region for the associated power rails and shows its sequential relationship to the transition regions of other power rails. The notes associated with the power sequence diagram provides further detail of these requirements. See the Power-up Sequence section for details on power-up requirements, and the Power-down Sequence section for details on power-down requirements.
Two types of power supply transition regions are used to simplify the power supply sequencing diagrams. The legends shown in Figure 6-3 and Figure 6-4 along with their descriptions are provided to clarify what each transition regions represents.
Figure 6-3 defines a transition region with multiple power rails which may be sourced from multiple power supplies or a single power supply. Transitions shown within the transition region represent a use case where multiple power supplies are used to source power rails associated with this waveform, and these power supplies are allowed to ramp at different times within the region since they do not have any specific sequence requirement relative to each other.
Figure 6-4 defines a transition region with one or more power rails which must be sourced from a single common power supply. No transitions are shown within the region to represent a single ramp within the transition region.