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MTaj-.2
MTaj-.2
Visitor II
July 13, 2022
Question

Selecting a Suitable Ultra-Low Power MCU

  • July 13, 2022
  • 3 replies
  • 4124 views

Hello,

I am using a Power Management IC with Digital output supply specifications in my project with very low power. The average digital outputs are: 1.8V, 85uA, 150 uW.

I am struggling to find a suitable low power MCU. Any suggestions?

For example, I looked at STM32L552ZET6Q (attached pdf, page no. 153 Current Consumption table) and the Supply current requirement in Run mode (Range 2) at lowest frequency (100 KHz) is 0.223 mA at 25 degrees Celsius which is higher than what my PM IC can supply (85 uA).

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3 replies

Andrew Neil
Andrew Neil
Super User
July 13, 2022

This sounds a bit odd.

Any microcontroller will usually start in its normal "running" mode - liable to take mA - it won't go to low-power until code puts it there.

Therefore a power supply that can only manage under 100uA seems very strange.

Maybe give some more details about your design - what are you trying to achieve?

What is this "Power Management IC" that you're using?

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
Andrew Neil
Andrew Neil
Super User
July 13, 2022

"What is this 'Power Management IC' that you're using?"

Is this some kind of energy-harvesting system, perhaps?

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
Peter BENSCH
Peter BENSCH
ST Technical Moderator
July 13, 2022

In addition to what @Andrew Neil​ said, for such ultra low power applications one typically takes an energy storage device, usually a capacitor, which is charged by the weak source. When a certain amount of energy has been buffered, the STM32 can start or be started and go back to sleep when the minimum voltage is reached.

Regards

/Peter

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