How get lowest sleep current in STM32F7508-DK

Sule_akcy · ‎2024-02-22

I am working with standby mode on the STM32F7508-DK board and measuring the standby current as 900mA. The tools I use in the program consist of LED and RTC for wake-up. What should I do to reduce this current?

SofLit · ‎2024-02-27

Hello,

There is this application note: AN4749 "Managing low-power consumption on STM32F7 Series microcontrollers".

The board used is 32F746GDISCOVERY which has the same config as yours. If it's not the case there may be some little differences/similarities that you could determine to have your measurement.

The section "2.2 How to use the application" shows how to measure the power supply.

The section "2.3 Power consumption measurements" provides some power measurements even in Standby mode.

Hope it does answer your question.

Also refer to the example provided in STM32CubeF7 under the path: https://github.com/STMicroelectronics/STM32CubeF7/tree/master/Projects/STM32F7508-DISCO/Examples/PWR/PWR_STANDBY

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SofLit · ‎2024-02-22

Hello,

How did you measure the current? 900mA seems the consumption of the board not the MCU!

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Sule_akcy · ‎2024-02-22

Yes, this measured current is the current of the MCU.

I measure current from the location of the R21 resistor.

SofLit · ‎2024-02-27

Hello,

There is this application note: AN4749 "Managing low-power consumption on STM32F7 Series microcontrollers".

The board used is 32F746GDISCOVERY which has the same config as yours. If it's not the case there may be some little differences/similarities that you could determine to have your measurement.

The section "2.2 How to use the application" shows how to measure the power supply.

The section "2.3 Power consumption measurements" provides some power measurements even in Standby mode.

Hope it does answer your question.

Also refer to the example provided in STM32CubeF7 under the path: https://github.com/STMicroelectronics/STM32CubeF7/tree/master/Projects/STM32F7508-DISCO/Examples/PWR/PWR_STANDBY

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

Sule_akcy · ‎2024-02-27

Thank you for sharing this information with me.
If you have sample code for this application, I would appreciate it if you could share it with me.
I will see where I made a mistake.

SofLit · ‎2024-02-27

The FW related to the described demo in AN4749 is downloadable from this link: X-CUBE-LPDEMO-F7.

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SofLit · ‎2024-02-27

If you are enable to build the projects I've attached hex files for your reference.

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Tesla DeLorean · ‎2024-02-27

Generally the DISCO boards are poor examples of "low power" implementations, there's a kitchen sink of hardware attached, and most can't be powered down in a meaningful way. Removed connected hardware until you hit expectations.

Most of the current you describe would be coming from what's attached.

But 900 mA??

The USB is only rated for 500mA at 5V, what's that 2.5 W full tilt, and the regulators are below that.

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