The STM32L series is what STMicroelectronics claims to be the industry's first ultra-low-power ARM Cortex-M3 microcontrollers, combining a dedicated low-leakage 130nm process technology and optimized power-saving architecture to deliver industry-leading energy-saving performance. The STM32L series is part of ST's EnergyLite platform of ultra low-power products enabling designers to optimize performance, functionality and battery life, and to meet efficiency-related criteria such as eco-design targets.

In addition to its energy efficiency, the STM32L series also has many features promoting data security and safe system operation, including flexible Brown-Out Reset; on-board Flash with Error Correction Code (ECC) support; a memory protection unit (MPU); and JTAG fuse.

These features are recommended for all applications that require safe product behaviour and highly secure code and user-data management. Integrated USB 2.0 full speed support also makes the devices 'handset ready'. Additionally, the MCU's embedded LCD drivers enable easier, cheaper and smaller application designs.

Joining the extensive STM32 family, which now has over 135 variants offering complete pin, software, and peripherals compatibility for maximum flexibility, the STM32L offers 33DMIPS at 32MHz and offers integrated Flash densities from 64Kbyte to 128Kbyte.

In addition to its underlying process-related power savings, the STM32L series provides numerous features allowing developers to optimize the power consumption of their applications. Six ultra-low-power modes allow the device to fulfill its tasks while consuming the least possible energy at any given time.

Based on preliminary figures at 1.8V/25°C, the available modes are :

10.4 microA Low-Power Run mode at 32kHz

6.1 microA Low-Power Sleep mode with one timer active

1.3 microA STOP mode: Real-Time Clock (RTC), context preserved, RAM retention

0.5 microA STOP mode: no RTC, context preserved, RAM retention

1.0 microA Stand-By mode: RTC, back-up register preserved

270 nanoA Stand-By mode: no RTC, Back-up register preserved

Two new low-power modes – 'Low-Power Run' and 'Low-Power Sleep' – have been implemented in the STM32L series, to drastically reduce power consumption at low frequency operation by using an ultra-low-power regulator and oscillator. The regulator allows current demand to be independent from the supply voltage.

The STM32L also offers dynamic voltage scaling, a well established power-saving technique that further reduces the internal operating voltage for medium and low operating frequencies. The current drawn, in normal Run mode, from Flash memory is as low as 230 microamps per MHz and the STM32L delivers a consumption/performance ratio down to 185 microamps/DMIPS.

In addition, the STM32L circuitry is designed to deliver high performance at low voltages, which enables battery-operated equipment to operate for longer before recharging. The integrated analog features are capable of operating at supply voltages down to 1.8V. The digital functions are able to operate from a supply voltage as low as 1.65V, allowing prolonged operation in battery-powered equipment as the battery voltage decays.

The chip is sampling now to lead customers, volume production will begin in Q4 2010.