Called STM32U0, the “MCUs can reduce energy consumption by up to 50% compared to previous product generations”, said the company. It “allows more designs to go battery-free, running solely from an energy-harvesting system such as a small photovoltaic cell”.

On the same day, ST announced future FD-SoI MCUs with phase-change memory

Picking the STM32U083xC at random, they run from 1.71 to 3.6V and consume 130nA in battery-backed mode with the real-time clock and nine 32bit registers sustained.

Run mode costs 52μA/MHz according to the front page of the data sheet, which goes on to say that in shut-down, with six wake-up pins active, this can drop to 16nA, increasing to 30nA in stand-by (8kbyte ram retained) with the same wake pins, or 160nA if the RTC is sustained as well. The lowest power Stop mode costs 695nA (825nA with RTC). Wake is in 4μs from the highest drain Stop mode.

Power consumption is aided by having two on-board linear regulators, one for running up to 56MHz, and a low power regulator for running at up to 2MHz – a low-power run mode.