Capacitive touch added to ultra-low-power MCUs

Renesas Electronics Corporation has introduced the RA0L1 MCU Group based on the Arm Cortex-M23 processor. The new devices offer extremely low power consumption and provide the industry's best solution for quickly and economically implementing capacitive touch in battery-powered and other consumer electronics, appliances, white goods, and industrial system controls.

The company introduced the RA0 MCU series in 2024, and it has quickly gained popularity with a wide range of customers due to its affordability and low power consumption. With the addition of capacitive touch functionality, the devices provide designers with the ability to create responsive, attractive, and low-power user interfaces at a very low cost.

The MCUs deliver industry-leading power consumption of only 2.9mA current in active mode, and 0.92mA in sleep mode. In addition, an integrated High-speed On-Chip Oscillator (HOCO) allows the fastest wake-up time for this class of MCU. The fast wake-up enables the RA0L1 MCUs to stay in Software Standby mode more of the time, where power consumption drops to a minuscule 0.25µA. With this feature, current consumption can be decreased by up to 90% compared with other solutions.

The RA0L1 devices have a feature set optimised for cost-sensitive applications. They offer a wide operating voltage range of 1.6V to 5.5V, so customers do not need a level shifter/regulator in 5V systems. The MCUs also integrate multiple communication interfaces, analogue functions, safety functions, and security functionality to reduce customer BOM costs. A wide range of packaging options is also available, including a tiny 4mm x 4mm 24-pin QFN.

Additionally, the new MCU's high-precision (±1%) HOCO enhances baud rate accuracy, enabling designers to eliminate the need for a standalone oscillator. Unlike other HOCOs in the industry, it maintains this precision in environments from -40C to 125C. This wide temperature range enables customers to simplify thermal design by eliminating the need for costly and time-consuming 'trimming' after the reflow process.

The company offers industry-leading capacitive touch technology, enabling customers to implement high-quality touch interfaces quickly and cost-effectively across a range of systems. Its self-capacitance method simplifies waterproof design, offering a simpler design and reduced complexity compared to mutual capacitance solutions. Its multi-frequency measurement meets IEC61000 4-3 Level 4 standards, making it excellent for medical applications that demand robust protection from EMI. The company also offers specialised development resources for capacitive touch, including the QE for Capacitive Touch, which streamlines sensitivity adjustments for capacitive touch buttons, thereby speeding up development.

"The RA0L1 combines the industry-leading power consumption and cost-effectiveness of our RA0 Series MCUs with our unmatched capacitive touch technology and tools," said Daryl Khoo, vice president of the Embedded Processing Marketing Division at Renesas. "We look forward to the many innovative touch interface solutions that our customers will create using these devices."

Key Features of the RA0L1 Group MCUs:

• Core: 32MHz Arm Cortex-M23
• Memory: Up to 64KB integrated Code Flash memory and 16KB SRAM
• Extended Temperature Range: Ta -40C to 125C
• Timers: Timer array unit (16b x 8 channels), 32-bit interval timer (8b x 4 channels), RTC
• Communications Peripherals: 3 UARTs, 2 Async UART, 6 Simplified SPIs, 2 I2C, 6 Simplified I2Cs
• Analogue Peripherals: 12-bit ADC, temperature sensor, internal reference voltage
• HMI: Capacitive Touch (up to 24 channels), Controlled Current Drive Port (up to eight)
• Safety: SRAM parity check, invalid memory access detection, frequency detection, A/D test, output level detection, CRC calculator, register write protection
• Security: Unique ID, TRNG, Flash access window, Flash read protection
• Packages: 24-, 32- and 48-pin QFNs, 32-, 48-pin LQFP, 20-pin LSSOP

The new RA0L1 Group MCUs are supported by the company's Flexible Software Package (FSP). The FSP allows faster application development by providing all the infrastructure software needed, including multiple RTOS, BSP, peripheral drivers, middleware, connectivity, networking, and security stacks as well as reference software to build complex AI, motor control and cloud solutions. It enables customers to integrate their own legacy code and choice of RTOS with FSP, thus providing full flexibility in application development. Using the FSP will ease migration to and from other RA family devices.