MCUs for smaller, longer-lasting smart devices

6th November 2018
Alex Lynn


With a focused feature set and compact package options, STMicroelectronics’ STM32L412 and STM32L422 microcontrollers (MCUs) aim to bring ultra-low power technologies and high performance to budget-conscious consumer, industrial, and medical applications.

Whether the squeeze is on core performance, energy, physical space, or bill of materials, the new MCUs give more freedom to beat the constraints. Combining economical 64 or 128Kbyte Flash density with features such as ST’s FlexPowerControl (FPC), and the 80MHz Arm Cortex-M4 core, they set best-in-class EEMBC benchmarks for efficiency and performance: 273 CoreMark provides for speedy execution in devices like smart sensors or consumer wearables, while 167 ULPMark-PP (Peripheral Profile) and 447 ULPMark-CP (Core Profile) demonstrate category-leading energy management.

Developers can turn the winning benchmark figures into tangible product advantages, leveraging features such as the multiple reduced-power modes to maximise battery life. Analog peripherals including two ADCs to perform simultaneous acquisition and a comparator integrate more of the signal chain on-chip, for sensing or heart-rate monitoring. Moreover, extra package options including five by five millimetres LQFP32 or 2.58x3.07mm WLCSP36, save component count and board space.

A choice of temperature grades, specified from -40 to +85°C or +125°C, withstand tough conditions in industrial or medical applications. Flash error correction (ECC) and parity-checking hardware for on-chip SRAM enhance system safety. A Quad-SPI interface allows high-performance off-chip memory extension and there are rich peripherals for control and connectivity.

In addition, high dynamic efficiency ensures great performance in smart meters, drawing as little as 28µA/MHz. The integrated ADCs, anti-tamper inputs on battery and backup-power domains, a true random-number generator (TRNG), and support for AES-256 encryption in the crypto-enhanced STM32L422 ensure high accuracy and strong protection.

Leveraging dedicated extensions to the STM32 ecosystem including the STM32CubeL4 software package and STM32CubeMX initialisation-code generator and power-consumption calculator, developers can start working with the new devices immediately. Two new Nucleo boards also join the ecosystem, including the NUCLEO-L412RB-P containing a 64-pin STM32L412 with step-down converter, and the NUCLEO-L412KB with a 32-pin STM32L412. The new devices come with ST’s 10-year product-availability assurance.

The STM32L412 and STM32L422 are in production now, with up to 128Kbyte Flash and 32-pin to 64-pin packages, priced from $1.51 for the STM32L412K8U6 with 64KByte Flash in QFN-32, for orders of 10,000 pieces per year.

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