Dynamic Voltage Control
Dynamic Voltage Control (DVC) is a technology that has other names but all refer to essentially the same technique: to dynamically vary the voltage supply (V_DD) to a digital circuit (CPU) in conjunction with simultaneous modulation of the clock rate. It is based on the principle that CMOS digital logic can reliably operate at lower V_DD voltages if the clock rate is temporarily reduced as well. This condition usually correlates to “sleep modes” for the system where workload is relatively low and full computation speed is not required. Both parameters (voltage and clock) are usually software controlled and based upon awareness to system operation mode and anticipated CPU instruction load. This technique reduces power consumption in the digital circuit according to the following basic equation:

P = f * C * V²

Where:
f = clock frequency
C = CMOS capacitance (constant)
V = V _DD voltage

It can be seen that a typical 10% reduction in V_DD along with a 50% reduction in clock speed yields a 68% reduction in overall power consumption (vs. 50% with clock modulation only). This extra 18% of power savings is acheived without any additional penalty to the performance other than the 50% due to the clock rate reduction.

Figure 2. (Voltage, Clock, Power diagram)

Summit Programmable Power Manager ICs have the ability to dynamically adjust their output voltages very accurately over a wide range of analog values with slew rates that are controlled and predictable. Additionally, the I²C interface on the Summit ICs connects directly to most system controllers so that the DVC can be implemented directly in the system software with no intermediate circuitry.

If all digital electronic systems used this technology it is estimated the global power savings would be on the order of gigawatts, which represents multiple power generating plants and millions of tons of CO₂ emissions each year. Summit DVC technology is featured in the following products:

SMB122
SMB120
SMB117
SMB113A
SMB112
SMB111
SMB110
SMM105
SMM205
SMM150
SMM465
SMM605
SMM665
SMM764
SMM766