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developers' ability to find the optimum balance of power and performance. More advanced MCUs such as Analog Devices' ADuCM4050 remove many of the traditional barriers to power optimization. With its broad complement of integrated features, the ADuCM4050 can support requirements at multiple levels of the IoT hierarchy. For IoT edge computing, the MCU's ARM Cortex- M4F processor core and integrated cryptography accelerator provide the capabilities needed to execute increasingly complex algorithms for edge analytics or machine learning applications or deliver low-latency responses in control-loop applications. For IoT sensors and actuators, the MCU's extensive set of on-chip peripherals and safety features enable developers to meet broad requirements for data collection and control of operations in process control, automation, and other precision IoT applications. In any of these systems, designers can take advantage of multiple ADuCM4050 features available for managing power. Developers can place the MCU in multiple low-power modes that reduce current consumption from levels as low as 1.27mA in active mode down to 50nA in shutdown mode. Intermediate power modes such as hibernate mode let developers maintain state and some wake-up interrupts at only 0.65μA. ADuCM4050's Flexi mode keeps the processor core inactive while maintaining power to the rest of the device, resulting in current consumption of only 400μA. Nevertheless, the MCU needs only about 1.6μs to transition from Flexi mode to active mode. Consequently, developers can keep the MCU in Flexi mode to read a stream of bytes from a sensor with minimal power consumption before waking the core to complete any data processing operations. The ADuCM4050 lets developers further trim power consumption by employing techniques including enabling on-chip cache, selecting the amount of SRAM retained in hibernate mode, and using an on-chip oscillator as a wake-up source. By combining low-power sensors and AFEs with the ADuCM4050 MCU, developers can create battery-powered IoT devices capable of delivering the streams of data needed for enterprise applications. For many of these applications, developers can optimize power through careful selection of the connectivity technology itself. For example, sub-gigahertz wireless technologies offer an inherent advantage for low-power design due to the inverse relationship between received RF power and communication frequency. On the other hand, mesh networks take advantage of the ability of individual nodes to relay messages, enabling developers to build networks of low-power devices to cover a physical area much larger than any individual device's RF transmitter can reach on its own. Wireless SoCs such as Analog Devices' ADF7030-1 and LTC5800 provide solutions for sub-gigahertz and mesh networking, respectively. These devices combine ARM Cortex-M series real-time MCU cores with an RF transceiver supported by a complete on-chip RF signal chain including a Low-Noise Amplifier (LNA) in the receiver path and PGA in the transmitter path. Developers working with tight power budgets can trade power and performance, reducing power consumption by lowering transmitter output. As with other devices described in this article, developers can even place the LTC5800 mesh network SoC in a very low-power doze mode between brief wake periods scheduled for network communications. Besides the use of low-power devices and related power conservation methods, designers face an added requirement unique to these battery-powered IoT devices—that of the incorporation of suitable capabilities for extending, recharging, or monitoring the battery itself. In fact, developers can rapidly implement those respective features in their designs with Analog Devices' LTC3330 battery extender, LTC3331 battery charger, or LTC3335 battery monitor. The LTC3330 and LTC3331 each integrate a high-voltage energy harvesting power supply to fully meet the device's power requirements by converting available ambient energy typically found in abundance in a factory, office, or even a typical home. Built around the same switching regulator design, the LTC3330 extends the life of a primary battery while the LTC3331 charges a rechargeable battery. Power selector circuitry in each device automatically switches the supply source to the energy harvesting supply when ambient energy conversion reaches the required threshold level (Figure 3). 14 Learn More 4 Learn More 4 Figure 3: Analog Devices' LTC3330 extends the life of a primary battery by rapidly switching to its energy harvesting supply source when that source exceeds threshold levels. (Source: Analog Devices) IoT

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