Products & Solutions

ARC® Energy PRO Power Savings

Case Study: Wireless Traffic Management

Energy PRO technology puts the designer in control of the balance between performance and power consumption: not just during the design cycle but at execution time as well.

One of the key attributes of Energy PRO is its ability to create hardware that can adapt to the changing external demands placed upon it. This capacity is especially valuable in environments where processing requirements are “bursty”. An application such as wireless connectivity management – for instance in WiMAX or WiFi equipment – is typical.

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Like many communications applications, this example includes periods of high and medium traffic; and often lengthy periods during which there is no traffic at all. Using a processor such as the ARC EP30 gives the designer access to multiple power management modes to “shape” the performance and power consumption of the entire system.

The device will generally only have to deliver peak performance for a few seconds each minute – perhaps 10 to 15 percent of the time when peak traffic is encountered. Nevertheless the system must be designed to accommodate these peaks of activity. During these periods, the EP30 runs at its maximum 200 MHz clock rate and core operating voltage of 1 V.

More commonly – in this example around 20 percent of the time – the system will be handling moderate traffic. In this case, the designer can program the system to self-select a low-power mode with the clock scaled to 50 MHz, and the core voltage reduced to 0.7 V. This produces a substantial cut in power consumption, to 3.62 mW – and an even greater saving in total energy.

Finally, when there is no traffic at all, the device may move into its lowest-power shutdown mode, consuming just 50 µW. Depending on the usage model, this is in fact likely to be the most common state, lasting 60 to 70 percent of the time.

The result is dramatically reduced power consumption at all times, except the brief window of peak traffic. The consequent six-fold cut in total energy requirements translates to significantly increased battery life in the case of a portable application.

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