Mouser - White Papers

Mouser Electronics White Paper Meanwhile, cradle-to-grave analysis includes costs such as transportation to deliver the product to the end customer, energy consumption during the product's useful operating life, and end-of-life disposal. A relevant LCA metric is product carbon footprint (PCF), a measure of total greenhouse gas emissions over the complete supply chain throughout the product's life, from raw material extraction to waste disposal (Figure 5). For semiconductors, PCF can vary based on the fabrication location, the process used, and the packaging, even for otherwise identical designs. But in general, regardless of manufacturing conditions, use-phase energy represents the largest environmental impact over a product's life cycle. Key Sustainable Design Considerations for Engineers When designing with a focus on sustainability, engineers should emphasize three critical areas: optimizing power efficiency, ensuring regulatory compliance and future- proofing, and selecting components that support long-term availability and material efficiency. Power Efficiency and Performance per Watt Due to high energy requirements during a product's use, power efficiency is a primary driver for lowering total energy consumption and greenhouse gas emissions over a product's life cycle. For a microcontroller unit (MCU), the data sheet typically provides power consumption specifications in milliwatts (mW) or energy efficiency metrics such as CoreMark®/mW or current per megahertz (µA/ MHz). In addition, various benchmarks can help estimate the device's expected energy usage for typical real-world workloads over the all-important use stage of the life cycle. One such benchmark is CoreMark, 6 which, compared to other benchmarks, has the benefit of representing the performance of the processor itself rather than a compiler that could compensate for processor deficiencies. Figure 5: Total carbon footprint per device, broken down by life cycle stage. Each color segment within the chip shows the CO₂ impact of raw materials, production, transport, use, and end-of-life. (Source: STMicroelectronics; modified by Mouser Electronics) For a device such as an MCU, several design techniques can boost energy efficiency for a given workload. These techniques include dynamic voltage and frequency scaling (DVFS), near-threshold logic, and power gating, as well as sleep and other low-power modes. The DVFS power-management technique adjusts voltage and frequency as needed, in real time, under software control based on a processor's workload. DVFS limits power consumption by reducing both voltage and frequency when the workload is low. This technique is scalable across a variety of applications, ranging from mobile devices, where it can extend battery life, to data centers, where it can reduce overall power consumption. Near-threshold technology can significantly boost power efficiency by operating transistors near or slightly above their threshold voltage (typically 0.3–0.6V), which is significantly below standard supply levels (typically 0.9–1.2V). This technique reduces dynamic power consumption, specifically when the MCU is in normal run mode, which represents a major part of an application's total energy consumption. Normal run mode typically accounts for 80 percent of the usage time for industrial equipment and 99 percent of the usage time for consumer electronics devices. Consequently, reducing dynamic energy consumption improves overall energy efficiency and reliability, contributing to fewer part replacements and site visits for stationary equipment, in addition to longer battery life for mobile devices.

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