Renesas Unveils Smallest 8-pin Package Option in RL78 MCU Family

January 16, 2023 by Aaron Carman

A new microcontroller from Renesas brings general-purpose performance to its smallest form factor.

Adding to its RL78 family of low-power microcontrollers (MCUs), Renesas recently announced the release of its newest member: the RL78/G15 general-purpose MCU. The newest offering includes industry-standard hardware but in a new, smaller form factor. The decreased package size is aimed at engineers looking to reduce system size while maintaining expected performance.


The RL78/G15 MCU

The RL78/G15 MCU is offered in various package sizes, with a minimum pin count of 8 in a 3 mm x 3 mm package. Image used courtesy of Renesas


In addition to the new MCU, Renesas is also releasing a Fast Prototyping Board (FPB) to help engineers evaluate the effectiveness of the RL78/G15 in their own use cases and libraries to speed the development of applications using the G15 series of the RL78 family (datasheet linked here). This article will examine some of the key features of the latest release from Renesas and the target applications and supporting material surrounding the device to help designers determine if this new MCU is right for their projects. 


Performance in a Small Package

The G15 line of the RL78 family contains standard specifications that make it suitable for a wide variety of applications. The 16-bit CPU core operates at 16 MHz, and the MCU includes either 4 KB or 8 KB of code flash memory. Depending on the number of GPIO pins required, the MCU is available with a pin count from 8 pins to 20 pins, with the smallest 8-pin package measuring only 3 mm x 3 mm.


The block diagram for the RL78/G15 MCU

The block diagram for the RL78/G15 MCU highlights the primary features of the device. Image used courtesy of Renesas


Despite the small size of the device, the thermal performance demonstrates that the MCU is anything but fragile. The device is rated to operate within temperatures from -40°C to 125°C, ensuring that designers are not limited in their placement of the MCU. As an added benefit, the chip supports several communication protocols such as SPI, UART, and I2C, making it versatile in integrating with existing systems.


Getting Started with the RL78/G15

Designers looking to integrate the RL78/G15 into their own projects do not need to start from scratch. As part of the G15 release, Renesas has also released an FPB that contains the RL78/G15 MCU at its core (specifically the 20-pin R5F12068ASP). With interoperability in mind, Renesas included both Arduino and PMOD headers to give designers a way to rapidly connect existing circuits to the board.


The FPB layout

The FPB layout highlights the board's features and illustrates how Arduino shield or PMOD-compatible devices can be connected. Image used courtesy of Renesas


Programming the RL78/G15 is made simple using the Renesas Smart Configurator GUI tool (part of the CS+ IDE), which allows designers to rapidly generate cookie-cutter program frameworks based on their own needs. In addition, an Arduino library is available for the FPB, which provides a quick solution to be designed using the board and the resources of the Arduino platform.


A Welcome Addition to the RL78 Family

Aiming to demonstrate its effectiveness, Renesas has already released a reference design using the G15 MCU. Integrated alongside power electronics chips, the G15 series MCU is used as part of a 100 W multiple-output USB PD adaptor. While it may not be a solution that all engineers can draw from, it does act as the first of many tests for the G15 series’ effectiveness as a general-purpose MCU.

At the moment, information surrounding the G15 chips is still scarce. Both the G15 datasheet and user manuals require an update to include packaging information for the 8-pin device, and notably, the 8-pin devices are currently missing from the G15 product page (10-, 16-, and 20-pin devices are still offered). Regardless, the release of the G15 line gives designers a new choice when choosing MCUs, especially for those looking to shrink their designs without shrinking performance.