ST Tightens MCU Security

The STM32H5 family updates STMicroelectronics’ high-performance-MCU line with additional security. Installing the new Secure Manager software on the flagship model can yield a complete security suite with no required coding.

Bryon Moyer

The STM32H5 MCU family updates STMicroelectronics’ high-performance-microcontroller offering with additional hardware security. Combined with the company’s new Secure Manager software, designers can implement precertified security with no coding. Targeting industrial and consumer electronics, the Cortex M33-based family has a low-cost entry version and three siblings with up to 2 MB of flash memory.

Hardware security features range from debug authentication in the smallest model to acceleration of multiple algorithms and inclusion of an immutable root of trust (RoT) in the flagship model. Two-stage secure boot provides an immutable RoT in the first stage and an updatable RoT in the second. Intermediate models feature Arm’s TrustZone trusted execution environment (TEE).

Clocking at up to 250 MHz—nearly a 40% increase from prior Cortex M4-based units—all models achieve 375 Dmips and 1,023 CoreMarks. Typical active current is 61 μA/MHz (a 75% reduction); standby current is 3.5 μA (a 50% improvement) with a 3 V VDD from a switching power supply, which bypasses the integrated low-dropout (LDO) regulator to boost power efficiency.

Built in ST’s 40 nm process, compared with the prior units’ 90 nm, two family members are in production now using select packages; the remainder are scheduled for a 2Q23 release. The company provisions the top models with multiple unique physical IDs and the immutable RoT at manufacturing; OEMs can download and install the Secure Manager binary during their manufacturing, although they’re free to employ their own security software instead.

Secure Manager isn’t tied to this particular MCU family, but if installed on the flagship unit (the only model that can host the software), it achieves Security Evaluation Standard for IoT Platforms (SESIP) level 3. ST owns and maintains the software; it can provision certificates in manufacturing and provide updates in the field.