These are boom times for energy harvesting applications. Much attention has been focused on the U.S. government’s investment in clean energy and private industry’s investment of $400 billion “in clean energy manufacturing, EVs and batteries, and clean power generation. Less publicized are the burgeoning markets for low-power energy harvesting applications for IoT, wearables, and biomedical devices such as implants.ii
Demand for highly efficient, reliable, and compact energy storage applications highlights the potential of harnessing ambient energy to replace or supplement rechargeable batteries for low-power devices. Such energy harvesting applications promise potentially indefinite operation without having to replace batteries, which can dramatically reduce eco-waste.
Harvested solar energy can power wearable devices, communications devices, remote or hard-to-reach sensors, and a wide variety of smart devices in retail, industrial, and residential environments. But designers can also harness other ambient energy sources including temperature variations, motion, vibrations, radio waves, and acoustic sound.
Overcoming design challenges
Size and power management are critical challenges in designing mobile, remote, and unattended devices. In many cases, wireless connectivity is equally challenging. However, continuing progress in integrating and miniaturizing the necessary electronic components allows developers to reduce device footprints and optimize costs.
Identifying suitable energy sources and optimizing power consumption are critical factors in developing successful applications. Form factors and aesthetics will vary greatly, depending on the intended environment and usage.
Consumer devices must be cosmetically attractive and meet high standards of usability to achieve market success. Industrial and remote devices are less impacted by aesthetics and consumer-friendly operability, but will likely have to achieve greater levels of functionality and interoperability.
Implementing a low-power design will hinge mainly on finding the right components and software to minimize energy consumption. It may also depend on maximizing power extraction from the energy source. Ideally, applications can harvest more energy than is consumed to achieve complete energy autonomy.
High-performance, energy harvesting PMIC
Nexperia offers a power management integrated circuit (PMIC) designed to continuously harness ambient energy. The NEH2000BY (Figure 1) addresses a typical energy harvesting trade-off by enabling high performance of devices without compromising on energy efficiency.
The Nexperia PMIC uses an adaptive algorithm for Maximum Power Point Tracking (MPPT) to optimize energy transfer from ambient sources and ensure high conversion. Operating autonomously without pre-programming, the NEH2000BY MPPT algorithm achieves an optimum average conversion efficiency of up to 80% and adapts within 0.5 seconds.
MPPT is no doubt familiar to developers working on or exploring solar panel and wind turbine optimization, but it can also be used for applications harvesting other ambient energy sources such as thermal, vibrational, and radio signals. MPPT continuously monitors voltage and current to identify optimal power and adjusts the load to match the output to application requirements.
Utilizing a “hill-climbing” algorithm, the NEH2000BY adapts to changing environments and ensures maximum efficiency, regardless of energy fluctuations. While optimized for photovoltaic applications, the PMIC can work with a variety of harvester devices that utilize storage element voltage in a range of 2.5 V to 4.5 V, and is compatible with various types of rechargeable batteries, as well as battery-less designs.
The Nexperia PMIC enables designers to create applications utilizing an integrated, high-efficiency, low-power DC-DC, eliminating the need to add a converter and bulky external inductor. It requires just one external capacitor, simplifying the printed circuit board (PCB) layout and cutting down on the application’s bill of materials.
Available in a 3 mm x 3 mm plastic thermal enhanced very thin quad flat package (HWQFN), the PMIC requires a total assembly area of just 12 mm, according to Nexperia. This enables harvesting designs up to 20 times smaller than existing solutions.
Reference design platform
Product designers can prototype and test energy harvesting applications with a reference design platform that reflects a collaboration between Nexperia and Ambiq.
The Ambiq harvestKIT AMA3BHARV1 (Figure 2), combines a click module based on Nexperia’s NEH2000BY PMIC with Ambiq’s Apollo3 Blue SoC and low-power 1.8 V custom Click sensor modules from TDK InvenSense and Bosch Sensortec.
The harvestKIT provides energy harvesting from Nexperia with a micro-electromechanical systems (MEMS) motion sensor and an environmental sensor. The Apollo3 Blue SoC integrates Bluetooth Low Energy (BLE) 5. An additional expansion socket can support other sensors and connectivity modules such as Wi-Fi or a display.
The components can drive applications combining low-power energy harvesting with inputs such as temperature, humidity, motion, and pressure monitoring.
Developers can utilize the reference design to develop a range of prototypes that can extend battery life by harvesting energy, or eliminate the use of batteries by incorporating supercapacitors or other energy storage components.
The Apollo3 Blue SoC utilizes Ambiq patented Subthreshold Power Optimized Technology (SPOTÒ) to manage harvested energy and efficiently process low-power applications. The reference platform firmware sends raw sensor data to a web app that runs on a Chromium web browser on a phone, tablet, or PC.
Conclusion
Nexperia’s PMIC offers an attractive design option for next-generation energy-efficient applications. By harnessing solar energy and integrating advanced sensor modules, developers can create innovative solutions that significantly extend battery life and potentially remove their need altogether. Nexperia’s collaboration on Ambiq’s harvestKIT AMA3BHARV1 reference design provides a prototyping and testing platform for cutting-edge, low-power management and processing applications, addressing the growing demand for sustainable and efficient electronic devices.
Source : Digikey Blog
