Future Picks — Renesas RL78/G21 and RL78/G23 16-Bit Microcontrollers (MCUs)

The Right MCU Platform for Low-Power Control and Advanced HMI

With home appliances, smart-home products and consumer devices become more connected and feature-rich. Designers are looking for MCUs that can deliver more functionality without increasing system cost or power consumption.

The Renesas RL78/G21 is a NEW cost-effective general-purpose 16-bit MCU designed for low-power, cost-sensitive system-control applications. The RL78/G23 (R7F104G) builds on this platform with enhanced capacitive-touch capability for applications where an intuitive user interface is just as important as system control.

Together, the RL78/G21 and RL78/G23 provide a flexible MCU platform for system control, connectivity and HMI, helping address evolving requirements across smart appliances, consumer electronics and industrial equipment.

The Right Balance of Cost, Power and Functionality

The RL78/G21 focuses on the fundamentals that matter most in cost-sensitive, embedded designs. Its low RUN current supports energy-efficient operation, while its competitive positioning in the 128KB and 256KB classes makes it well suited to applications where MCU cost is an important part of the overall BOM.

The RL78/G23 provides a natural step up when an application requires more advanced HMI functionality. Its enhanced capacitive-touch capability and higher touch-channel configurations enable designers to create intuitive control panels, touch interfaces, and new interaction concepts.

Both devices benefit from the established RL78 ecosystem, providing a practical path from initial evaluation and prototyping through production.

Key Features

The RL78/G23 combines low-power operation with advanced touch functionality. Renesas specifies low CPU operating current, low stop-mode current with SRAM retention, operation across a wide voltage range and speeds up to 32MHz, depending on device configuration. The family also incorporates the CTSU2L capacitive sensing unit and logic/event link controller.

For touch-focused designs, the RL78/G23 achieves a ULPMark™-PP score of 125 and an average touch current of 10.8 μA, demonstrating its focus on efficient HMI operation.

Applications

The RL78/G21 and RL78/G23 are well suited to products where cost, energy efficiency, functionality and ease of development need to come together.

From MCU Evaluation to a Working Prototype - FPB-RL78G21 Fast Prototyping Board

Getting an MCU into the hands of a designer early can make a significant difference to development time. The FPB-RL78G21 Fast Prototyping Board provides a convenient starting point for evaluating the RL78/G21 and developing proof-of-concept designs.

Designers can explore MCU functionality, peripherals, communication interfaces, power requirements and firmware concepts before committing to a custom PCB.

The Fast-Prototyping Board approach helps simplify development, allowing designers to quickly move from MCU evaluation to a working prototype and ultimately toward a production-ready design.

Scalable HMI Development

The RL78/G23 provides a path for designers who want to introduce or expand touch functionality while staying within the Renesas ecosystem.

Its capacitive-touch technology can support everything from simple touch controls to more advanced HMI concepts, while Renesas QE tools help simplify implementation.

For product families, the platform provides flexibility to select the right MCU for the application: RL78/G21 when cost-effective system control is the priority, and RL78/G23 when enhanced touch and HMI functionality are required.

A Practical MCU Solution for the Next Generation of Designs

The RL78/G21 and RL78/G23 bring together the capabilities designers need to develop smarter products while keeping cost, power consumption and development effort under control. Whether your main priority is efficient system control, enhanced touch functionality, or rapid prototyping, the RL78 platform provides a scalable path from initial concept to production.