To understand how much better technology and design have become when it comes to power management, one need look no further than a mobile phone, says Embedded Consultant Matt Liberty. “My phone’s battery life of one day is no different that 20 years ago, but what I can do with my phone has changed dramatically. “
Liberty, the founder of Jetperch LLC, a software and hardware engineering consultancy and creator of Joulescope, an easy-to-use, affordable test instrument for low-power design, spoke with FierceElectronics about the challenges of creating energy efficient designs. The main takeaway: “Do more with less.”
FE: What Is the most problematic aspect of power management for design engineers today?
Liberty: Most experienced engineers have a good understanding of how to do the upfront design. However, the time pressure to quickly produce a working prototype sometimes outweighs concerns about energy consumption, and it’s hard to shoehorn low energy consumption into a design after the fact.
Even when you do good engineering upfront, the challenge once you have working hardware and software is actually figuring out and fixing what in the design is consuming the unexpected, extra energy. While this is reasonably straightforward with simple products, such as a BLE sensor, it can get very challenging and time consuming to quantify and then optimize the energy consumers in large, more complex products.
FE: Obviously the design trade-off space for any type of electronic product is massive. What can engineers do at the start of a design to help meet the energy budget for their designs?
Liberty: Energy consumption is just one product feature. For devices that need to do a lot of data processing, it is critical to ensure that you have the most power-efficient hardware—that means selecting that low-power microcontroller, microprocessor, FPGA, or neural net IC. Product size and volume bounds the maximum battery capacity. For simple RF sensors, the update rate to the network is often the limiter.
The easiest way to meet your power budget is to strategically manage complexity in your design Keep things simple wherever possible, especially for the areas of the system where energy is critical. If possible, push complexity to a part of the system where energy is a less critical product requirement.
FE: What are some of the most common approaches to effectively reduce energy consumption?
Liberty: The most common method is to simply do less. Keep the microprocessor, microcontroller, and hardware in their lowest power sleep state for as much time as possible.
For more data-intensive products, making the tradeoff between local data processing, which yields data reduction, or more RF communication is definitely a challenge. Both processing and RF communication take energy. Striking the right balance is often quite difficult for new products, when the actual amount of data processing is often not fully understood in the early stages of the design. For this class of systems, a good strategy for reducing that uncertainty and helping to find the right balance early in the product development cycle is to roughly prototype the processing using off-the-shelf hardware .
Many products have lots of unknowns at the beginning of the project. Each of those unknowns has the potential to blow the energy budget. Tackling those unknowns early not only reduces the project risk, but it also helps the team make informed decision regarding energy consumption.
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Don't miss keynoter Matt Liberty and a panel discussion with power management experts, on tips and tricks for to achieve energy efficient designs and a peek at new technologies on the horizon, during the Power Management Track at Sensors Innovation Week digital event, July 16-17, 2020. Register now for this free event.