[SOLVED] STM32L0 really lower power than STM32L4? (ARM Cortex M0, M4)

Hello everybody,

I'm choosing an ultra low power microcontroller for an application with RTC and long sleeping times. I have been looking at the numbers from the brochures and datasheets from STML4 and L0 and I can't find a reason why L0 is better in power consumption. I post some numbers from the website:

STM32L4
Ultra-low-power mode: 8 nA with backup registers without real-time clock (5 wakeup pins)
Ultra-low-power mode + RTC: 200 nA with backup registers (5 wakeup pins)
Ultra-low-power mode + 16 Kbytes of RAM: 170 nA
Ultra-low-power mode + 16 Kbytes of RAM + RTC: 450 nA
Dynamic run mode: down to 84 μA/MHz
Wake-up time: 5 μs
source: https://www2.st.com/content/st_com/...l4-series.html?querycriteria=productId=SS1687

STM32L0
Dynamic run mode: down to 87 μA/MHz
Ultra-low-power mode + full RAM + low power timer: 440 nA (16 wakeup lines)
Ultra-low-power mode + backup register: 250 nA (3 wakeup pins)
Wake-up time: 3.5 µs
source: https://www2.st.com/content/st_com/...l0-series.html?querycriteria=productId=SS1817

First of all, dynamic run mode is slightly worse for L0; then, Ultra-low power mode + RTC looks way better for L4 than L0's ultra low power mode, and on top of that, L0 doesn't have an 8 nA shutdown mode. The only significant difference I found on tables and graphs from the ST website is that the L4 has much higher memory and performance than L0, which has no FPU......

Could somebody please enlighten me and tell me how to exploit the ULP capabilities of L0?

Thanks and kindest regards,
Oscar

Hello people,

I have read further and I still don't find a convincing reason for using L0. Anybody has some idea to share?

Greetings,
Oscar

From power consumption of view I recomend you to take a look at Stellaris family from Texas Instruments.

Easyrider83 said:

From power consumption of view I recomend you to take a look at Stellaris family from Texas Instruments.

Click to expand...

Hi Easyrider,
I took a look to LM3S9B9 for instance and the current is at least in mA range and 30 uA for the hibernation mode. That's completely out of my budget.

Could you or somebody else try to address the STM32L4/L0 question?

Thanks and regards,
Oscar

Hi oscarto,

As you mentioned one of the differences between STM32L0 and STM32L4 is the core:

STM32L4 is based Cortex-M4 providing up to 100DMIPS and therefore targeting applications requiring high processing/computation performance and low power.

STM32L0 is based on the Cortex-M0+ which is a low power optimized version of the Cortex-M0. here, CM0+ is targeting application executing simple task that requires competitive price and low power.

As both products are targeting different applications there are offered in different memory range and package choice:
STM32L4 is available from 256KB to 1MB flash memory; package from 32pins and up to 132pins
STM32L0 is available from 8KB to 192KB flash memory; package from 14pins and up to 100pins

Both products are based on ultra low power technologies:
STM32L4 has outstanding dynamic and static power consumption.
STM32L011 goes down to 76uA/Mhz dynamic (Run mode).
Comparing the datasheet the STM32L0 static consumptions are slightly higher than STM32L4 at 25degree. But at high temperature the L0 will have better power consumption.
The STM32L0 ADC is optimized to consume only 48uA at 100KSPS
STM32L0 has an embedded true EEPROM

I would say there are both ultra low power MCUs with tiny power consumption but there are not targeting the same application.

BR
rictus

The way the OP phrased the question this sounds like an academic question where he is simply trying to understated the differences in the technology. However the subsequent responses from the OP suggest to me that he is trying to actually make a circuit design choice.
If so then there is one critical question that needs to be answered from a practical point of view: what is the lowest supply current that he needs? If the design requires that the overall current be less than some amount (for longer battery life or whatever) then it could well be that BOTH devices (and probably others as suggested) will do the job as both can operate below the required threshold and so this does not really matter. Of course the converse could also be true but without know the the actual requirement it is hard to tell!
Susan

Sorry for the delay. Thanks a lot. Finally I found a reasonable answer to my question.

1. L4 came after L0, so they tried to equal or even improve the low power figures. That is why comparing the numbers is so misleading.
2. However, in running mode L0 can still be driven by a lower clock frequency e.g. 10 kHz, resulting in a lower power running mode, not available in the L4's.

Thanks everybody.
Kindest Regards,
Oscar