1. Field of the Invention
The present invention relates to an embedded system having designated power partitions, wherein the voltage of each partition in each state can be independently controlled, thereby facilitating power reduction in the embedded system.
2. Discussion of the Related Art
The power consumption of a system is related to its capacitance, clock frequency (frequency), and power supply voltage (voltage). Specifically, the power consumption is proportional to its capacitance and frequency, and the square of its voltage (i.e. dynamic power=C*V2*f). Changing the capacitance is process dependent (i.e. a product of manufacturing) and thus is not controllable by the end users of the system. Therefore, end users of the system can attempt to change the frequency and the voltage to reduce overall power consumption.
For example, end users can change the frequency and the voltage based on the functions required by the system. Generally, the higher the frequency needed, the higher the voltage needed to sustain that frequency. It logically follows that the lower the frequency needed, the lower the voltage needed to sustain that frequency. A divided digital clock can be used to change the frequency substantially simultaneously with a command. However, a predetermined period of time is needed to switch the voltage. Therefore, a control circuit can be used to issue a voltage change command before the frequency change command, thereby ensuring an optimal frequency and voltage for the system at any point in time. U.S. Published Patent Application 2004/0090808, entitled “Power-Supply Voltage Frequency Control Circuit”, published on May 13, 2004, describes such a control circuit.
Typically, software is used to determine when to make a voltage and frequency change. Unfortunately, because a number of applications may be running on the operating system at any one time wherein each application may have different requirements, software may not know the optimal time to make the voltage and frequency change. Therefore, taking into account a worst-case scenario, software may opt to use a high voltage and frequency for the system, thereby undesirably increasing power consumption.
An increasing number of integrated circuits (ICs) include a set of functionalities tailored for a specific application. An exemplary application could be to implement a device in a wireless local area network (WLAN). These types of ICs are referred to in the industry as “embedded systems”. These functionalities, although supporting a specific application, may require significantly different voltages and/or frequencies. Therefore, a need arises for a system and method of providing optimal power profiles to an embedded system.