Embedded Controller Based on Renesas’ SOTB to Power IoT Devices


Renesas’ energy harvesting embedded controller eliminates the need for batteries by reducing current consumption which was not possible in conventional MCUs

Renesas Electronics Corporation, launched an innovative energy-harvesting embedded controller that can eliminate the need to use or replace batteries in IoT devices.


The new embedded controller R7F0E based on Renesas’ SOTB (silicon-on-thin-buried-oxide) process technology, reduces current consumption in both active and standby mode. This combination was not previously possible to achieve in conventional microcontrollers (MCUs).

These extreme low current levels of the SOTB-based embedded controller enables system manufacturers to take a step further and completely eliminate the need for batteries in some of their products through harvesting ambient energy sources such as light, vibration, and flow.

Key Features of the R7F0E Embedded Controller

  • CPU: Arm Cortex-M0+
  • Operating frequency: Up to 32 MHz, and up to 64 MHz in boost mode
  • Memory: Up to 1.5 MB flash, 256 KB SRAM
  • Current consumption while operating at 3.0V:
    – Active: 20 µA/MHz
    – Deep Standby: 150 nA with real-time clock source and reset manager
    – Software Standby: 400 nA with retention of core logic and 32 KB SRAM data, real-time clock source, reset manager
    – SRAM data retention consumes 1nA per KB of SRAM, optionally up to 256KB
  • Energy Harvesting Controller (EHC): Interface for direct robust connection to energy generating devices, and for charge management of energy storage devices
  • Analog-to-Digital Converter (ADC): 14-bit, 32KHz operation frequency, 3µA consumption
  • Graphics: 2D graphics data conversion and MIP display interface
  • Security and Encryption: True random number generator, a unique ID for each R7F0E device, AES encryption acceleration
Consumer Hard Drives With Improved Capacity & Performance

R7F0E Reduces Challenges for System Designers to Achieve Low Power Design:

R7F0E eliminates many challenges faced by system designers who want to build cost-effective products with efficient energy harvesting capabilities. There is a unique and configurable Energy Harvest Controller (EHC) function that increases robustness and minimizes costly external components. The EHC enables direct connection to many different types of ambient energy sources, such as solar, vibration, or piezoelectric, while protecting against harmful inrush current at start-up. The EHC also manages the charging of external power storage devices such as supercapacitors or optional rechargeable batteries.


The use of extreme low-power and energy harvesting gives rise to a new market of maintenance-free connected IoT sensing devices with endpoint intelligence for applications in
industrial, business, residential, agricultural, healthcare, and public infrastructure, as well as health and fitness apparel, shoes, wearables, smart watches, and drones.

About Renesas’ SOTB process technology

The unique SOTB process technology originated by Renesas realizes extreme reduction of both active and standby current, which has typically been a trade-off and is not possible to achieve in conventional MCU process technologies. On the silicon substrate, an oxide film (BOX: buried oxide) is buried under a thin silicon layer on the wafer substrate. No impurities are doped to the thin silicon layer which makes it possible to maintain stable operation at low voltages. The devices can therefore deliver high computing performance with excellent power efficiency. At the same time, the potential of the silicon substrate below the BOX layer is controlled with a back bias circuit to reduce leakage currents to further suppress standby power consumption.

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Samples of the new R7F0E embedded controller are available now for beta customers, and samples are scheduled to be available for general customers from July 2019. Mass production is scheduled to start from October 2019.

This technology will be demonstrated by Renesas at Electronica from November 13 to 16.

“I am very pleased that Renesas achieved this milestone to productize our SOTB technology into a first-of-its-kind solution in the energy harvesting market,” said Yoshikazu Yokota, Executive Vice President and General Manager of Industrial Solution Business Unit of Renesas. “By removing the need for batteries, or the need to replace batteries, new markets will open for us and our customers. Energy harvesting will become a mandatory technology for a smart society and Renesas is poised to lead and expand this technology, and this market. Renesas continues to push forward with e-AI to realize AI at the endpoint, in embedded devices. Looking forward, our SOTB technology will expand our reach into use cases where combining e-AI and energy harvesting will make a very large positive impact to our day-to-day lives.”

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