STMicroelectronics has announced its ultra-low-power STM32L5x2 microcontrollers (MCUs) that emphasize security to assure better protected IoT-connected applications. Operating at clock frequencies to 110MHz, the STM32L5-series MCUs start from the Arm Cortex-M33 32-bit RISC core with Arm TrustZone hardware-based security. First conceived for equipment such as desktops, mobile devices, and communication infrastructure, trusted computing authenticates devices connected to a network by creating a protected execution environment for cyber-protection and sensitive code (cryptography and key storage) that blocks attempts to corrupt devices or software. A second, independent, execution environment allows for the running of untrusted code.
To this foundation, ST adds the freedom to include or exclude each I/O, peripheral, or area of Flash or SRAM from TrustZone protection, allowing sensitive workloads to be fully isolated for maximum security. In addition, ST has engineered TrustZone to ensure support for secure boot, special read-out and write protection for integrated SRAM and Flash, and cryptographic acceleration, including AES 128/256-bit key hardware acceleration, public key acceleration (PKA), and AES-128 On-The-Fly Decryption (OTFDEC), to protect external code or data. The STM32L5 also supports active tamper detection and secure firmware installation. With this attention to security, the STM32L5 has been certified to PSA Certified Level 2.
The device also mixes in ST’s proprietary ultra-low-power expertise through techniques like adaptive voltage scaling, real-time acceleration, power gating, and multiple reduced-power operating modes, to enable the MCUs to deliver high performance and long run-times, whether powered by coin cells or even through energy harvesting. In addition, a highly efficient switched-mode step-down regulator can be powered up or down on-the-fly to improve low-power performance when the VDD voltage is high enough. The resulting ULPMark scores, which are key measures of ultra-low-power efficiency based on real-world benchmarks developed by EEMBC, are excellent: 370 ULPMark-CoreProfile and 54 ULPMark-PeripheralProfile at 1.8V.
The STM32L5x2 MCUs offer 512KB dual-bank Flash that allows read-while-write operation to aid device management and the Flash ensures a high level of safety by supporting Error Correction Code (ECC) with diagnostics. There is also a 256KB-SRAM and features to support high-speed external memory including single, dual, quad or octal SPI and Hyperbus flash or SRAM, and an interface for SRAM, PSRAM, NOR, NAND or FRAM.
Digital peripherals for the STM32L5x2 include USB Full Speed with dedicated supply, allowing customers to keep USB communication even when the system is powered at 1.8V, and a UCPD controller compliant with USB Type-C Rev. 1.2 and USB Power Delivery Rev. 3.0 specifications. Smart analog features include a state-of-the-art analog-to-digital converter (ADC), two power-gated digital-to-analog converters (DAC), two ultra-low-power comparators, and two operational amplifiers with external or internal follower routing and programmable-gain amplifier (PGA) capability.
As part of the industry-leading STM32 family of MCUs, the STM32L5 series is fully supported by the STM32 ecosystem and features its own STM32CubeL5 one-stop-shop software package, which includes Hardware Abstraction Layer and Low-Level drivers, FreeRTOS, Trusted Firmware-M (TF-M), Secure Boot and Secure Firmware Update (SBSFU), USB-PD device driver, MbedTLS and MbedCrypto, FatFS file system, and Touch Sensing drivers.
In addition, the STM32CubeL5 features more than 300 project examples that can run on the STM32L552E-EV evaluation board, STM32L562E-DK discovery kit, and NUCLEO-L552ZE-Q. These projects can be compiled with the Arm Keil development tool, IAR or STM32CubeIDE toolchains, and are delivered with a STM32CubeMX configuration file, enabling easy customization and code update.
Starting at $2.60 in 1k quantities, the STM32L5x2 MCUs are in full production and available now in standard temperature grade (-40°C to +85°C) for consumer and commercial applications, or high-temperature grade specified from -40°C to +125°C for challenging environments.
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