IoT devices will be able to add unprecedented new value by incorporating sensors and communication functions in all things around us. The IoT devices are mostly battery powered with expected operational life of 10 years or more. Also, the IoT devices are often equipped in places out of reach for people, and the maintenance costs of these batteries including the labor costs are enormous. To solve these challenges, longer battery life and energy harvesting are needed, and IoT devices and MCUs are required to have high energy efficiency without sacrificing speed and performance.
IoT device developers are demanding a fair and objective criterion on evaluating energy efficiency of multiple MCUs. The ULPMarkTM -CoreProfile (ULPMarkTM -CP) developed by EEMBC (*1) is an objective benchmark to measure the energy efficiency of MCU accurately. The Core Profile focuses on the MCU’s core, specifically the energy cost in standby, and the transition to and from active mode. The Core Profile runs a workload on a one-second duty cycle with an extended period of inactivity to enable the use of microcontroller low-power modes. The score is inversely proportional to energy consumption, hence a higher score refers to higher energy efficiency.
Fig. 1 ULPMarkTM -CP Score Calculation Overview
In April 2020, the RE Family achieved EEMBC certification with a ULPMarkTM -CP score of 705, demonstrating the world's highest level of power efficiency. Compared to a general-purpose MCU with a ULPMarkTM -CP score of 100, the RE Family is 7 times more power efficient. Assuming only the MCU’s CPU is operated with batteries of the same size and capacity, the battery life can be translated into 7 times longer. Compared to the other MCUs registered on the EEMBC website, the RE Family has a higher score of about 300 or more in most cases. This shows that the RE Family is the best choice for IoT applications requiring a longer battery life.
Fig. 2 Estimated Longer Battery Life Using RE Family
(*1) The Embedded Microprocessor Benchmark Consortium (EEMBC) is a nonprofit industry group that works to promote standardization of benchmarks. The major MCU suppliers such as Renesas Electronics, STMicroelectronics and Texas Instruments are also board members.