Newest Dialog Semiconductor PMIC Tackles Big IoT Design Issue: Extending Battery Life for Wearables

November 20, 2018 by Kate Smith

Dialog Semiconductor's newest PMIC (power management IC) aims to help solve the battery life issue with wearables and other small, portable applications.

Dialog Semiconductor's newest PMIC (power management IC) aims to help solve the battery life issue for wearables and other small, portable applications—a now-familiar challenge for many IoT device designers.

Last week, Dialog Semiconductor released their latest PMIC designed to manage power for IoT devices that need to extend their battery life (presumably most of them). 

To learn more, AAC spoke with Faisal Ahmad, Dialog Semiconductor's Director of Marketing for their power management and audio products within mobile systems business unit. 

Here's a look at this IC's most important features, the significance of fuel gauges in wearables, and where the wearables market is going.

Power Management for Small IoT Applications

The DA9070 is a nanopowered PMIC designed to power IoT equipment. One of the major focuses of this product is wearables such as fitness trackers, but IoT here could also mean smart home or building automation applications or even key fobs.

The goal is to extend the life of small batteries, especially in those applications where there's some kind of always-on functionality (say, a sensor for home automation or a clock for a wearable).

This chip consumes very low quiescent current while maintaining voltage regulation required by the components in the system. 

To accomplish this, the DA9070 features the following components:

  • Battery charger for rechargeable battery
  • Buck regulator to power the system's MCU
  • Boost regulator to power display or high-voltage sensor
  • Three linear regulators to power other I/Os or sensors
  • Analog battery monitor to create a fuel gauge for the device 


Block diagram for the DA9070. Click to enlarge


A Low-Power Fuel Gauge

This last feature, the fuel gauge, is an important one. Oftentimes, small IoT devices have a bar indicator for gauging how much battery remains (e.g., three bars indicates ~75% battery life remaining where two bars indicates ~50%). Ahmad says this is because fuel gauges generally consume a lot of current, draining the battery that they're measuring. 

"Our fuel gauge only consumes 4μA and actually runs in the system MCU so it's very low-cost," he says. "It takes voltage and current information from our PMIC and creates the fuel gauge." 


The fuel gauge interface


Use this gauge functionality is eased by software available of Dialog's website, including "a full set of software that walks you through the process of creating a fuel gauge." 


The DA9070 Dev Board

The DA9070 has a dev board for designers to work with. The board comes with a 80mA hour battery, a common size for, say, a fitness tracker. In addition to the PMIC there's also included a typical MCU (an m4 ARM Cortex core) loaded with Dialog Semiconductor firmware to measure voltage and current and to run the algorithm to create fuel gauge. 


The DA9070 dev board


An Integrated Solution with Some Flexibility

Problems with small designs often require solutions with small footprints. As Ahmad puts it, "We're solving the problem with a highly integrated solution because many of these systems are very small." 

While this level integration is important for this particular PMIC, according to Ahmad, it's also "flexible enough where various regulators can be used for different circuits" depending on what's going on in the system. 

"This part is perfect for someone who's got the challenge of trying to fit their circuity in a small space and make their battery last as long as possible," he says. "Every component of the device is really tuned for optimizing battery life. Everything can also be controlled digitally through an I2C interface so—if you're a system designer who's got more of a background in embedded design, writing code into an MCU—it makes it really easy to control the device with the driver we provide and control everything digitally." 


Dialog Semiconductor and the Future of the IoT

Ahmad believes that the wearables market is still relatively new. It's only been a handful of years, he points out, that we've been able to acquire fitness trackers in major stores. In the coming years, he thinks that wrist wearables may consolidate some. "But," he says, "we're still seeing a lot of innovation and new ideas for just wearables other than [those that are worn on the] wrist." Indeed, the wearables umbrella is widening, including jewelry like rings and pendants, shoes, and even textiles straight into clothes. 

One of the reasons that the wearables market is likely to continue to grow, Ahmad says, is that "generally speaking, one of the main driving forces of having wearables is improving your health. That's a big market. It should be a priority for most people. If you're helping do that, there will always be an opportunity there."

For Dialog Semiconductor, this is good news. "We do see [the IoT space] growing. In general, for our power management, we're all about efficiency and extending battery life," Ahmad says. "And this is a market in which that's the big problem—so it's a great fit for us from a technology perspective."



What challenges have you come across when trying to power small IoT devices? What methods have you used to try to solve them? Let us know in the comments below.