Texas Instruments OMAP36 Series, Technical Reference Manual, Page: 227 / 3738

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Introduction to Power Managements
maximum operating frequency (left side of the figure), it terminates in 1 second, and the remaining 3
seconds are spent in idle mode. With DVFS (right side of the figure), the operating frequency is reduced to
an optimal level; the task takes the full 4 seconds to complete, but power consumption is reduced. In
addition, voltage can be further reduced to save power so dynamic and leakage power consumption are
reduced.
DVFS requires control over the clock frequency and the operating voltage of the device elements. By
intelligently switching the individual elements of the device to their optimal operating points, it is possible
to minimize the power consumption of the device for a given task.
For practical reasons related to device making (flow, tools), DVFS can be used for only a few discrete
steps, not over a continuum of voltage and frequency values. Each step, or operating performance point
(OPP), is composed of a voltage (V) and frequency (F) pair. For an OPP, the frequency corresponds to
the maximum frequency allowed at a voltage, or reciprocally, the voltage corresponds to the minimum
voltage allowed for a frequency.
When applying DVFS, a processor or system always runs at the lowest OPP that meets the performance
requirement at a given time. The user determines the optimal OPP for a given task and then switches to
that OPP to save power.
3.1.2.2 SmartReflex Adaptive Voltage Scaling (AVS)
SmartReflex™ is a power-management technique for automatic control of the operating voltage of a
module to reduce active power consumption.
With SmartReflex, power-supply voltage is adapted to silicon performance, statically (based on
performance points predefined in the manufacturing process of a given device) or dynamically (based on
the temperature-induced real-time performance of the device). A comparison of these predefined
performance points to the real-time on-chip measured performance determines whether to raise or lower
the power-supply voltage.
SmartReflex achieves the optimal performance/power trade-off for all devices across the technology
process spectrum and across temperature variations.
Figure 3-2 shows an example of SmartReflex power management.
Figure 3-2. SmartReflex Example
In Figure 3-2 , the self-adjusting voltage scaling with SmartReflex ensures the frequency performance of
the current OPP. For a given device operating frequency, the device voltage is automatically adapted to
maintain performance of the device. This ensures optimal power consumption for a given OPP.
227 SWPU177N – December 2009 – Revised November 2010 Power, Reset, and Clock Management
Copyright © 2009–2010, Texas Instruments Incorporated