 STM32L5 low power modes. As already mentioned before, STM32L5 has wide variety of operating modes. In this picture you can see the overview. Starting from the top, there is a run mode. We can notice that for maximum system frequency, which is 110 MHz, the consumption is on a level of 10.5 mA. Of course, it's possible to reduce the system clock. For 80 MHz and 26 MHz, the consumption is 6.8 mA and 1.8 mA respectively. In case of significant system clock reduction, for example down to 2 MHz, it's possible to use low power run mode. In such case, the consumption is on a level of 320 mA. In sleep mode, the core is stopped, while rest of the resources can be active, including high speed clocks. By keeping the same frequency as previously, so 2 MHz, consumption is reduced to 230 mA and wake up time is very fast, just 14 clock cycles. Then we have 3 stop modes. In these modes, both core and peripherals are stopped. These are typical low power modes, where MCE is waiting for an interrupt to wake up and resume the application. Depending on type of stop mode, consumption is different, wake up time is different, and also number of wake up sources is different. The lowest current consumption can be achieved by using standby, shutdown or VBAT mode, down to just few nanoamps. However, we need to consider limited number of wake up sources and longer wake up time. STM32L5 offers a variety of low power modes and it gives you the flexibility to select the most suitable one for your application. When deciding about low power mode, there are some parameters to consider, like the average consumption, peak current, performance or the reaction time. For example, standby mode fits to the profile where average consumption must be very low, reaction time does not need to be quick and time between wake up cycles is long. On the other hand, low power sleep could be a good idea for a profile where the reaction time has to be quick and there is a short period between wake up cycles. A good stride of between the two with low average consumption and short reaction time is stop 2. STM32L5 is clearly an ultra low power MCU family. So it's important to highlight that among different MCUs with ARM Cortex M33 available on the market, STM32L5 will give you the best in class ultra low power capabilities. In terms of low power mode, here you can see a comparison between STM32L5 and another device based on the same core. If we compare stop mode, standby mode and shutdown mode with their equivalents from competition, we can notice a huge difference. Both in terms of consumption and wake up time, STM32L5 is multiple times better than competitor. In this last demonstration, I would like to show you a typical example of low power application. The firmware will perform ADC acquisition with 1 kHz rate. When the sample acquisition is finished, the microcontroller will enter stop 2, which means that all high speed clocks are turned off and internally the chip is supplied from the low power LDO. After wake up, just before the next sample acquisition takes place, the microcontroller will continue executing exactly at the point where it left before. The content of the memory and the state of the processor is retained in stop 2. I will also measure the consumption again thanks to the cube monitor power and the power shield. The purpose of this demonstration is to show the importance of the wake up time and the consumption in low power mode, in this case stop 2. In this picture, you can see the transition table between various low power modes on STM32L5. For this particular example, we are going to use run mode at 4 MHz to take the sample and then enter stop 2 once it's finished. Let's now have a look at the consumption profile for 1 ADC sample acquisition. When the STM32L5 is in stop 2, the consumption is just a few microamps. When it wakes up and the core starts to execute at 4 MHz, the consumption is at a level of hundreds of microamps, so it's very important that the active phase is as short as possible. To wake up from STM2, it takes approximately 5 microseconds. To start the ADC acquisition, to store the value and clear the wake up flags, take less than 30 microseconds. So the rest of the 1 millisecond window, which is the acquisition rate of this application, can be spent in stop 2. To achieve low power consumption, it's necessary to have low duty cycle between the active and inactive phase. Having a short wake up time is absolutely essential to achieve this goal. So now I will flash the test binary, again by drag and dropping to the STLink mass storage. I will connect to the power shield. Let's set the sampling frequency again to the maximum, 100 kHz. And let's set the acquisition time for 100 millisecond. So what we should see is a consumption profile during 100, exactly 100 sample acquisition. And let's apply the target with 3 volts. Again I will start the acquisition for the second time. And here what we see is the periodic pattern during the ADC acquisition. What we don't see is the sharp transition between stop 2 and run mode, but it's only because we are measuring on a shunt resistor close to the power supply. So the waveform is sort of low pass filtered. Nevertheless, the average current consumption is correct. The microcontroller consumes 47 microamps in this particular application.