DocID17369 Rev 2

3/13

AN3193

STM32L1xx main features

13

1

STM32L1xx main features

Based on the solid foundations of the award-winning STM32F10x family, the STM32L1xx

embeds various innovations which minimize the consumption in different configurations,

while maintaining most of the existing peripherals and a quasi pin-to-pin compatibility.

For a given manufacturing process and die area, the consumption of a microcontroller

largely depends on two factors which can be controlled dynamically: voltage and frequency.

In the STM32L1xx devices, an internal low drop regulator supplies most of the logic circuitry

with a fixed voltage: this guarantees that consumption is kept minimal whatever the supply

voltage, along the lifetime of portable battery-supplied products, down to 1.65 V.

If we consider the clock sources, several cascaded clock prescalers, gating techniques and

peripheral-by-peripheral clock management allow only the necessary logic gates to be

activated, and at the adequate frequency. These are now design practices commonly used

for reducing the consumption in Run mode. For the STM32L1xx, additional efforts have

been done in this direction with the implementation of voltage scaling to reach an even

higher processing efficiency.

However, all ultralow power requirements cannot be met by simply focusing on run time: for

most applications, the challenge is to spend the minimum time and energy in this mode and

find the adequate low power mode.

The improvements do not come only from the deep sleep modes optimized to eliminate

every ten nA of leakage. The system has also been complemented with seven low power

modes and a set of peripherals tuned for low power (such as the calendar real-time clock

and glass LCD controller). These items are described in more detail hereafter.