Power Management: Throwing Down The Gauntlet

Customers say it’s not enough for smart phones to last a day between charges. Are phone makers listening?


By Frank Ferro
The recent burst of articles challenging smart phone battery life has me asking the question, “Are we ready to turn the corner on power consumption?” About two years ago I was bemoaning the fact that we are willing to live with a smart phone that gets only one day of battery life (Powering Forward or Moon Walking). As of today, nothing has changed. We still need to charge the phone every day. Recent processor announcements continue to be about adding more CPU cores (i.e. more performance). Not to pick on any one company, but did the announcement of an 8-core processor significantly change the smart phone? Is this product creating anticipation in the market for a new processor with 16 cores? Not really.

For most of us, all we want is a smart phone that has a reliable voice connection with a fast Internet browser and decent battery life. Okay, I watch short video clips on my phone, use the maps, along with a few cool apps, but do we need HD quality on the small screen? Even as Mobile World Congress is kicking-off in Barcelona this week, I saw ST-Ericsson announced their new NovaThor L8580, the first smart phone processor to hit 3GHz speed mark. Putting aside the debate about if and when a 3GHz processor is needed in a smart phone, speed still is getting attention.

There is hope, however, for those of us that don’t want to always carry around a power cord. Google and Motorola are making noise about upcoming products that will focus on battery life. Google CEO Larry Page said, “Battery life is a huge issue. You shouldn’t have to worry about constantly recharging your phone.” Consumers also are weighing in (finally), expressing their dissatisfaction with battery life. In a recent J.D. Power survey of smart phone users, they say that battery performance is becoming a critical factor in overall product satisfaction. The report states that “satisfaction with battery performance is by far the least satisfying aspect of smartphones.”

Another interesting aspect of the report is that users of 4G phones gave battery performance lower rankings than 3G users. 4G phones apparently need to ping the base station more often looking for a 4G connection, and there are fewer of them than 3G base stations. Although this may be a temporary situation as 4G proliferates, early testing of voice over LTE (VoLTE) shows a significant reduction in battery life when compared to CDMA, so we are still in an uphill battle.

On the semiconductor side, companies will continue to compete with high-end SoCs that are loaded with features. However, recent consolidation of the application processor market is the first sign that these SoCs are reaching initial levels of product maturity. As with most product cycles, the goal for first- or second-generation products is to grab market share by getting to market quickly. In these early generation products, there is not too much care taken (typically) to be gate- and power-efficient. At the product level there are also signs that the smart phone market is starting to mature with the release of the first midrange and value-smart phones. This clearly will open up opportunities for the major SoC players to do cost and power reductions. It also will open up new opportunity for other SoC vendors to compete that missed the initial market cycle.

Product shrinks and removing features certainly will help power consumption as gate counts go down (or at least are not going up). In addition, current power management techniques—such as power switching, including dynamic voltage and frequency scaling—provide power savings, but is this enough? As SoCs are redesigned to meet the requirements of a segmenting smart phone market, this is a great opportunity for chipmakers to adopt much more aggressive power management techniques. For example, these complex SoCs include a collection of subsystems with multiple power and clock requirements that are grouped by ‘domains.’ These domains can be turned on or off based on the expected use cases (e.g., when I am listening to music I want video and all radios asleep), thereby consuming as little power as possible. Due to software complexity and interdependencies between domains, however, the number of domains that can be controlled is limited. Less domain control means that more parts of the chip are on. In addition, the switching speed at which these domains can be turned on or off needs improvement. The current ‘top down’ software-controlled view can be relatively slow, again leaving domains on much longer than necessary.

The good news is that the market will force the SoC manufactures to get much more aggressive about power management. The J.D. Power report also indicated that smart phone owners who are highly satisfied with their device’s battery life are more likely to repurchase the same brand of smart phone, so better power management is now a real competitive issue. Current SoC leaders must make it a priority to innovate around power management, implementing much more aggressive power saving techniques—or they run the risk of leaving the door wide open for competitors. The power gauntlet has been thrown down.

—Frank Ferro is director of product marketing at Sonics.