The term ‘mobile phone’ is almost a misnomer. That’s because today’s mobile is so much more than just a phone. Those of us in our 40s and 50s will remember, perhaps fondly, an era from the late-1990s when mobile phones were simply devices that allowed you to make regular audio phone calls when away from a landline. With simple pushbutton keypads and basic alphanumeric monochrome displays their most advanced ‘app’ might have been SMS text messaging.
Without being nostalgic, it’s also fair to say that mobile phones from that period would run for days without needing to be recharged. Modern smartphones, which bundle regular phone functions with music and video players, high-end video gaming, Internet browsing, GPS navigation and numerous other applications, struggle to get a day’s use from a single battery charge. Which is why there’s no shortage of advice on the Internet on how to improve the battery life of smartphones with all these latest gizmos.
One obvious difference to the previous generation of phones is the large, bright, color graphic display that now dominates phone designs. Not so visible but key to their performance is 3G and, more recently, 4G connectivity for high bandwidth data services, complemented by WiFi for local Internet connections. Then there are other wireless services, such as Bluetooth and GPS, all of which use power consuming radio circuits.
Consequently, despite the technological advances that have reduced the power consumption of individual components, it is the combined use of all these features that ultimately impacts battery life. Encouraging power conservation by dimming screen brightness and turning off Bluetooth and WiFi is all very well but such measures inevitably compromise user convenience.
To address the problem, phones are being designed with advanced Power Management Units (PMUs) that work with DC-DC converters, low-dropout (LDO) regulators and load switches to provide the different voltages required by the various ICs in a modern handset. By knowing how the phone is being used and with the help of sensors inputs, a PMU can cut power to circuits that aren’t required or reduce processing power for less demanding applications. For example, detecting when a phone is being held to a user’s ear for a voice call, allows the central processor to be put into a low-power sleep mode with the display switched off and touchscreen disabled.
Extending battery life using smart power management techniques is one answer. Another way to alleviate users’ concerns is to make it easier to keep phones charged. Wireless charging technology is already appearing in accessory battery covers and it won’t be long before it is integrated into new handset designs. Without doubt, placing a phone on a charging pad is a lot more convenient that plugging it in to a charger. But is it a case of “convenience over efficiency” as another blog post has suggested?