Smart meters and energy-efficient IoT devices have to walk a fine line. They need to run on small batteries for years, yet must also provide secure system control and support modern connectivity.
Renesas is targeting this space with its new RA4C1 microcontroller family, designed around an Arm Cortex-M33 core and equipped with a feature set tailored to metering and other low-power applications.
Balancing Power and Performance
At the heart of the RA4C1 is Renesas’ low-power process technology, which delivers an active current of 168µA/MHz at 80MHz. In standby mode, current draw falls below 1.8µA while still retaining the entire SRAM contents. A dedicated power domain supports a real-time clock, allowing designers to maintain timekeeping even during deep sleep with only a small coin cell. With support for input voltages down to 1.6V, the device is well-suited for battery-powered systems where designers want either longer runtime or the option to use smaller cells.
Security as a Baseline
Utility metering and access control systems are increasingly prime targets for tampering, making security a core design requirement. The RA4C1 integrates the RSIP-300 security engine, which operates as an isolated subsystem with its own control logic. Hardware support covers AES, ECC, and SHA acceleration, along with a true random number generator and 256-bit unique key storage. Together, these features enable secure key management and lifecycle protection, meeting the needs of modern metering standards while reducing the overhead on the main CPU.
Peripherals for Metering Applications
The RA4C1 is also shaped by the everyday requirements of meter design. Dual-bank flash up to 512KB supports reliable in-field updates, while 96KB of SRAM and 8KB of data flash handle system variables and logging. Peripherals include a low-power ADC for sensor interfacing, an on-chip temperature sensor accurate to within 1%, and a segment LCD controller to drive low-power displays. Communication interfaces range from CAN FD to I²C, SPI, SCI, QSPI, and UART, providing broad connectivity in industrial and IoT networks.
Supported by the Flexible Software Package
To accelerate development, the devices are supported by Renesas’ Flexible Software Package (FSP). The FSP provides drivers, middleware, RTOS support, and TrustZone integration, while allowing developers to reuse legacy code or migrate across the RA family. This software environment helps reduce bring-up time and gives engineers a clear path from prototype to production, whether in metering, smart locks, thermostats, or other low-power IoT nodes.
Outlook
With the RA4C1, Renesas has built a microcontroller group that directly addresses the needs of global metering markets. By combining ultra-low power consumption with strong security and a focused peripheral mix, it gives engineers the tools to design systems that are both efficient and trustworthy. Evaluation kits are already available, making the devices accessible for early design work in utility meters and energy-sensitive IoT products.
Learn more and read the original article on www.renesas.com
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