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Reducing the cost of operation is important to many embedded applications. The main component of operation cost is power consumption. Since many embedded systems are battery operated, reducing the power consumption allows longer intervals between battery replacement or charging. As an extreme example, in medical implant devices (such as pace makers), lower power consumption means fewer surgeries for battery replacement.
There is no standard for power consumption alone. Power consumption is related to performance. 1000 MIPS/watt is the current target.
There are several ways to reduce power consumption. One is to use new semiconductor technologies such as energy-efficient circuits and lower voltage logic. A CPU core voltage of 1.8 v or less is the state-of-the-art in process technology. The other way to reduce power consumption is to improve designs. Not all control circuits need to be run all the time. One way to reduce the power consumption is to put a subsystem into sleep mode when it is idling. In sleep mode, the processor shuts down parts of the circuit so that they do not consume power. These sleeping circuits can be woke up in response to external triggers, such as communication inputs or timer expiration.