SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The power-management techniques previously described have specific features and are most effective when used under the specific operating conditions of the device. Hence, the best active power savings are obtained by combining the DVFS, DPS, SLM, and AVS techniques. For a given operating state, one or more of the power-saving techniques can be applied to ensure optimal operation with maximum power saving.
AVS must be used at boot time to adapt the voltage to the process characteristics (strong/weak) of the device and then be used continuously to compensate temperature variations. AVS can also ensure the maximum available application performance of the device at a given OPP.
When medium application performance is required, or when application performance requirements vary, DVFS can be applied. The voltage and frequency can be scaled to match the closest OPP that meets the performance requirement.
When application performance requirements fall between two OPPs, or when a low application performance is required that is below the lowest performance OPP, DPS can be applied to switch to low-power mode.
When combining DVFS and DPS, the operating frequency must not be scaled to match the performance requirement without scaling the voltage. Lower operating frequency increases task completion time and reduces idle time. This prevents DPS or reduces its efficiency (DPS becomes more effective as idle time increases). Unless DPS cannot be applied for other reasons, for a given operating point of DVFS the operating frequency must always be set to the maximum allowed at a given voltage. This ensures optimal process completion time and application of DPS.
If DPS cannot be applied in a given context, scaling the frequency while keeping the voltage constant does not save energy; it does, however, reduce peak power consumption. This can have a positive effect on temperature dissipation and battery life.
SLM must be used when no applications are running and performance requirement drops to 0.
The OPPs shown in Figure 3-18 are only for indication and clarity of text. They do not correspond to validated OPPs of the device.