Renesas announced the RL78/G21 on 28 October 2026, a new 16-bit microcontroller aimed at the control boards inside air conditioners, refrigerators, washing machines and microwave ovens. It is not a wireless chip. It is the part that runs the motor, compressor and sensor logic, sitting next to whatever Wi-Fi or Thread module makes the appliance "smart". At the same time Renesas extended the RL78/G23 line with versions that have more capacitive-touch channels for control panels.

What the RL78/G21 brings

  • Power: 34 µA/MHz operating current, which Renesas says is nearly half that of the widely used RL78/G13.
  • Memory: 128 KB or 256 KB of code flash, 8 KB of RAM and 4 KB of data flash, which replaces an external EEPROM for settings.
  • Clock: an on-chip high-speed oscillator with ±1.0% accuracy, so no external crystal is needed. The core runs at up to 32 MHz.
  • Supply: 1.6 V to 5.5 V.
  • Robustness: ±4 kV HBM ESD tolerance, a feature only the G21 has in this announcement.
  • Interfaces: adds a UARTA serial interface compared with the RL78/G13, for example for extra sensors.
  • Safety and security: an IEC 60730 self-test library for appliance safety certification, flash read protection, a flash shield window, plus unique and customer IDs against cloning and tampering.

The chip is pin and function compatible with the RL78/G13 and RL78/G23, so manufacturers can move existing boards over with little redesign.

More touch keys on the RL78/G23

The new RL78/G23 (R7F104G) devices raise the number of touch channels from 14 to 24 on the 44-pin version and from 16 to 25 on the 48-pin version. Renesas pitches the G23 for appliances that want system control and the touch user interface in a single chip, and the G21 for cheaper boards that only handle control.

Price and availability

Both lines are available now. The RL78/G21 starts at $0.56 for the 128 KB, 44-pin LQFP version and $0.77 for 256 KB, in 10,000-unit quantities. For development there is the FPB-RL78G21 Fast Prototyping Board with a 64-pin, 256 KB RL78/G21. It has Arduino UNO, Pmod and Grove connectors, is programmed over USB, and Renesas provides an Arduino library for it, so the chip can be tried out in the Arduino IDE.

For home users, this is background technology, since nobody buys a washing machine for its microcontroller. But appliance makers count every cent and milliwatt on the control board, and Renesas pitches the G21's security features as an answer to "the growing need for more secure smart appliances". Lower power draw and protection against cloned or modified firmware on the control board are the parts of this launch that eventually reach the kitchen and the laundry room.