BradJolly

Advanced Techniques for Optimizing Battery Life

Blog Post created by BradJolly Employee on Apr 19, 2017

Once you have taken the steps described in the Simple Steps to Optimize Battery Runtime blog, you still have opportunities to reduce power consumption in your battery-powered device. Be sure to measure the actual current consumption before and after each change, and try to understand why the results are as observed. The more understanding you develop, the better you will be at predicting the effects of future changes. This will help you get future products to market faster with optimized battery runtime.

 

Hardware optimizations

Consider using a simple analog comparator instead of an analog/digital converter (ADC) to trigger certain functions. The ADC is likely to be more accurate and faster than the comparator, but it has longer startup time and consumes more current. The comparator continuously compares signals against a threshold, and for some tasks, this may be sufficient. For cases where you need the accuracy and versatility of the ADC, turn off internal voltage references on the ADC and use Vcc as the reference voltage if possible.

 

Use two-speed startup procedures that rely on relatively slow RC timers to clock basic bootup tasks while the microcontroller unit (MCU) waits for the crystal oscillator to stabilize. Be sure to calibrate these internal RC timers or buy factory-trimmed parts.

 

Firmware optimizations

Use event-driven code to control program flow and wake up the otherwise-idle MCU only as necessary. Plan MCU wakeups to combine several functions into one wakeup cycle. Avoid frequent subroutine and function calls to limit program overhead, and use computed branches with fast table lookups instead of flag polling and long software calculations. Use single-cycle CPU registers for long software routines whenever possible.

 

Implement decimation, averaging, and other data reduction techniques appropriately to reduce the amount of data transmitted wirelessly. Also, make sure to thoroughly test various wireless handshaking options in an actual usage environment to strike the ideal balance between wasting time on unsuccessful communication attempts and performing excessive retries.

 

Your oscilloscope will probably be useful in obtaining quick measurements for these current waveforms, and depending on the communication protocol, an oscilloscope may be the only instrument with the necessary bandwidth to make such measurements. However, once you know the bandwidth of your signal, you may be able to use a DC power analyzer or device current waveform analyzer to make these measurements. These devices will make measurements with better precision and to provide more detailed analysis, such as automatic current profiles.

 

By implementing these strategies and measuring current consumption throughout your development process, you will quickly optimize battery runtime and drive success in IoT and other battery-driven applications for you and your customers.

 

Learn more about maximizing battery life of IoT smart devices by downloading helpful applications notes and webcasts from Keysight.

 

Follow our Next Generation Wireless Communications blog and connect with our industry and solution experts as they share their experiences, opinions and measurement tips on a number of cellular and wireless design and test topics that matter to you.

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