Renesas' Ultra-Low Power RL78/L23 MCUs with Dual-Bank Flash for Smart Home Applications

Renesas has introduced a new 16-bit RL78/L23 microcontroller (MCU) group, which expands its RL78 line. These MCUs are aimed at smart home and consumer electronics applications. They operate at 32MHz, offer low power consumption (industry-leading), and are packed with key features for displays and touch interfaces. 

Being designed to use minimal power, the MCUs are exceptionally beneficial for battery-operated devices that largely operate in standby mode. The VL4 reference mode slashes the energy needed to drive displays by about 30%. The SNOOZE Mode Sequencer (SMS) takes care of refreshing the multiplexed LCD segment display without waking the main processor. The MCUs operate within a wide range of 1.6V to 5.5V and can work directly with commonly used 5V power supplies. Display and capacitive touch integration make user interfaces modern and user-friendly for appliances like cooktops and heating systems. Suiting applications that require minimal downtime, the Dual-bank memory allows seamless updates via FOTA (Firmware Over-the-Air).

The MCUs come with a development environment including tools such as Smart Configurator and QE for Capacitive Touch, aiding engineers in designing and prototyping systems more efficiently. Renesas' Heating Rice Cooker Solution, a part of its Winning Combinations, pairs the new MCUs with many other components from its portfolio. The new MCUs, their Fast Prototyping Board (FPB-RL78L23), and the Capacitive Touch Evaluation System (RSSK-RL78L23) are all available for purchase. On Mouser (US), the RL78/L23 R7F100LPL3CFB#UA0 variant is priced at $7.77 per unit in single quantities, with the cost lowering with quantity increments. 

Key Features

• 16-bit RL78 core, up to 32 MHz

• Ultra-low power: 109 μA/MHz, 0.365 μA standby

• 1 μs wake-up time

• Segment LCD controller with VL4 mode (~30% lower drive current)

• Capacitive touch sensing

• SMS (SNOOZE Mode Sequencer) for LCD refresh without CPU wake

• Up to 512 KB dual-bank flash with FOTA support

• Up to 32 KB SRAM, 8 KB data flash

• IH Timer (KB40), 3-channel induction heating control

• Wide voltage: 1.6 V to 5.5 V, direct 5 V support

• Temp range: –40 °C to +105 °C

• UART, I²C, CSI interfaces

• IEC60730 safety library

• Packages: 44–100 pin LFQFP, LQFP, HWQFN

Applications

• Smart home appliances

• Battery-powered devices

• IoT and metering systems

• LCD + touch HMIs

• Cost-sensitive embedded systems with FOTA

• Industrial 5 V equipment