Who has the lowest power MCU?Follow article
I'd be very careful posing this question in any public forum of any kind, real or virtual. It is like asking ten doctors for an opinion: you'll get ten opinions and be none the wiser.
Surely Google, knows the answer - “Google, Google, on the wall, who has the lowest power MCUs of them all?” The top 10 results from the search term "low power microcontroller" were as follows (bare in mind, Google matches my searches to my profile):
1. TI Ultra Low Power MCU (pay-per-click advert)
2. 32bit low power mcu RX100 (Renesas) (pay-per-click advert courtesy of Silica)
3. Ultra Low Power MCU - ARM Cortex-M0 from Freescale (pay-per-click advert)
4. MSP430 - TI (first true search result)
5. picoPower - Atmel
6. eXtreme Low Power - Microchip Technology
7. Ultra Low Power MCU - Silicon Labs
8. C8051F96x - Silicon Labs
9. EE Times article on this topic
10. Low-Power MCU - Maxim (yes, Maxim have MCUs)
Now I have a list of some potential suppliers to research. I also know that TI pays top dollar for advertising and Renesas is getting good promotion courtesy of Silica! And curiously, Silicon Lab's 8051 MCU is the first actual MCU device highlighted;, what about their newly acquired EFM32 devices from Energy Micro?
So having trawled the net with this topic in mind, Energy Micro, now part of Silicon Labs, seems the most balanced in describing the aspects of an MCU that are critical to achieving low power consumption . It’s a combination of factors, including a low-leakage technology for when the MCU is in a low-power state, a well performing CPU to quickly get tasks finished when active and autonomous peripherals that can undertake a certain amount of work without needing to wake the CPU up.
So, as Douglas Adams said in The Hitchhiker's Guide To The Galaxy, perhaps the reason we are not getting an answer that helps is because we are asking the wrong question. Perhaps the question should be "Who has the lowest power MCU for my application requirements?" And this is exactly where the fun starts!
As Peter Clarke (EE Times) in his article mentions, everyone wants to claim the moniker of “World’s Lowest Power MCU”. But a data sheet comparison (as listed in this article) only provides some guidelines that we could plug into a rough Excel sheet calculation based upon how we intend to exercise the part. Reading through the comments left by readers, we sift through the usual “10 doctor’s opinions”. Except I see, from my perspective, a ray of hope in the form of the person going by the name of ‘schneiderham’, and I quote:
“I am seriously considering doing my own comparison test--an all out brawl--of MCUs that manufactures' are claiming to have "The industries lowest Power MCU". I plan to create three typical Low power applications and then optimizing to each processor and comparing their power performance. So far in my list of possible MCUs are: MSP430 XLP AVR picoPower RL78 STM32L Energylite EFM32 Does anyone know if anyone else has done this? Does anyone else have a MCU they would suggest?”
Exactly! This is what we really need - a side by side comparison. Only one issue with this though, who has the time to install several toolchains and IDEs, learn enough about each MCU to be able to write a comparative application code and then have the money to invest in the necessary hardware (i.e. both development kits for the MCUs and test equipment that can measure accurately from nA to mA)?
Evidence online suggests this is a challenge that many of us face. So how do you really tackle this? When faced with a new low-power MCU design challenge, do you just stick with what you know, or do you review the market, if so how deep do you go? Mere data sheet comparisons or do you dive in and get your hands dirty? Do you have the time to undertake detailed research? Is your laboratory kitted out with the equipment to undertake such tests and is it available when you need it?
Please leave your commens below to discuss your approach to choosing low-power MCUs and what “low-power” means for your applications.