Renesas Electronics has expanded its popular RL78 family with the introduction of the RL78/L23 series – a new generation of 16-bit microcontrollers (MCUs) designed to power the next wave of human-machine interface (HMI) applications. Compact, cost-effective, and engineered for ultra-low power operation, these devices combine segment LCD control, capacitive touch sensing, and dual-bank flash memory to bring sleek, responsive user experiences to everyday products.

Source : www.renesas.com

From smart home appliances to IoT devices and metering systems, the RL78/L23 delivers a balance of performance and energy efficiency that makes it a strong candidate for modern battery-powered and display-based designs.

Power Efficiency That Extends Battery Life

One of the standout features of the RL78/L23 MCUs is their ultra-low power consumption. Running at 32MHz, these devices achieve an active current of just 109 μA/MHz and a standby current as low as 0.365 μA. With a wake-up time of only 1 μs, systems can spend most of their time in deep sleep and resume instantly when needed.

Renesas has also introduced a new VL4 reference mode for the LCD controller, which reduces LCD operating current by around 30% compared to earlier RL78 devices. Combined with the SNOOZE Mode Sequencer (SMS), which dynamically drives LCD segments without CPU intervention, the RL78/L23 helps minimize CPU wake-ups and conserve energy at the system level. The result: longer battery life, lower maintenance costs, and reduced environmental impact.

The MCUs support a wide operating voltage range from 1.6V to 5.5V, making them flexible enough to run directly from 5V power supplies used in appliances and industrial systems – often eliminating the need for external regulators.

Rich Peripherals for Modern HMI Applications

The RL78/L23 is built with HMI applications in mind, offering a mix of peripherals that simplify design while improving user experience:

Built-in LCD Controller: Supports up to 56 segment outputs and 8 common outputs for compact yet clear display designs.
Capacitive Touch Sensing: Up to 36 channels for responsive, intuitive touch interfaces.
IH Timer (KB40): Enables precise multi-channel induction heating control, perfect for smart kitchen appliances like cooktops and rice cookers.
Dual-Bank Flash Memory: Supports firmware-over-the-air (FOTA) updates without system downtime, critical for applications such as metering where uninterrupted operation is essential.
Integrated Sensors and Oscillators: Includes a temperature sensor and internal oscillator, helping reduce component count, PCB size, and bill-of-materials (BOM) cost.

This combination of display, sensing, and system management capabilities makes the RL78/L23 a strong foundation for consumer appliances, smart meters, HVAC systems, and other connected devices.

Key Specifications

16-bit RL78-S3 CPU core running at 32MHz
512KB flash memory (dual bank) and 32KB SRAM
8KB data flash with 100,000 program/erase cycles
Rich timer functions: general-purpose timers, inverter timers, Timer RJ, Timer KB, RTC
Analog functions: 12-bit ADC, 8-bit DAC, comparator, and temperature sensor
Serial interfaces: UART, I²C, SPI, CSI
Wide temperature range: -40°C to +105°C
Package options: 44-pin to 100-pin (LQFP, LFQFP, HWQFN)
IEC60730-compliant self-test library for safety-critical appliances

Developer-Friendly Tools

Renesas has paired the RL78/L23 with a streamlined development ecosystem to accelerate time-to-market. Tools include:

Smart Configurator for quick system setup
QE for Capacitive Touch for intuitive tuning and evaluation
Fast Prototyping Board (FPB-RL78L23) compatible with Arduino IDE
Capacitive Touch Evaluation System (RSSK-RL78L23) for in-depth testing

By providing both hardware and software tools, Renesas ensures that designers can validate concepts quickly and confidently transition to production.

Real-World Applications

The RL78/L23 is not just about features—it’s about enabling innovative product designs. Some example applications include:

Smart Touch Panels: Low-power MCU controls LCD and touch while integrating air quality and temperature sensing.
Kitchen Appliances: From air fryers to blenders, the MCU powers digital controls and ensures precise heating, motor control, and responsive interfaces.
Smart Rice Cookers: Dual-bank flash allows firmware updates without interrupting operation, while the IH Timer ensures accurate temperature management.
Meters and Industrial Devices: Reliable, low-power operation with continuous firmware updates for long-term stability and flexibility.

Winning Combinations for Faster Design

Renesas supports its customers with over 400 Winning Combinations—pre-tested system solutions that pair RL78/L23 MCUs with other Renesas devices, such as regulators, sensors, and power controllers. These ready-to-use reference designs reduce risk, cut development time, and help engineers deliver competitive products faster.

One example is the Induction Heating Rice Cooker Solution, which integrates the RL78/L23 with power management ICs and smart control solutions for a compact, energy-efficient design.

Availability

The RL78/L23 MCUs are now available, along with the Fast Prototyping Board and capacitive touch evaluation system. More details can be found on the Renesas website.

Renesas ships more than 3.5 billion MCUs annually, serving industries ranging from automotive to IoT and industrial automation. With the broadest portfolio of 8-, 16-, and 32-bit devices, Renesas continues to lead in delivering high-quality, energy-efficient, and secure microcontroller solutions. Backed by decades of expertise, advanced process technology, and a robust partner ecosystem, Renesas remains a trusted supplier for companies worldwide.

Final Thoughts

The RL78/L23 MCU series exemplifies Renesas’s commitment to advancing user-friendly, energy-efficient embedded solutions. By combining ultra-low power operation, rich HMI features, and seamless update capabilities, these devices empower designers to build smarter, more sustainable products—from the appliances in our kitchens to the meters in our cities.

With its combination of performance, cost-effectiveness, and developer support, the RL78/L23 is set to become a cornerstone in the next generation of intuitive and connected devices.

Author Profile

Vikky K: 20+ years embedded hardware design professional with a burning passion for teaching. Sharing the intricate world of embedded hardware is my mission and joy.