AN4365 datasheet(23/35 Pages) STMICROELECTRONICS

23 / 35 page

DocID025303 Rev 2

23/35

AN4365

STM32F4 current consumption measuring

Once the user has taken the measurement, he should press the button to wake-up

from sleep and pass to the next sub-mode or mode.

•

If Stop mode is defined, proceed as described for Sleep mode.

•

If Standby mode is defined, press the button to enter the selected standby sub-mode.

If the sub-mode is with RTC and the wake-up button is not pressed, the device will

wake-up and reset after 20 s. The user should make the measurement before wake-up.

If the defined sub-mode is without RTC, the user should press the button to wake-up

the device after finishing the measurement.

The user should be aware about some constraints while performing the measurement:

•

For Run, Sleep and Stop modes, the user should put the ammeter in mA scale. For

Standby mode, the user should switch to the µA scale of the ammeter to be able to

measure the standby current.

•

It is recommended to connect the power supply source to the discovery board only

after power-on at the defined voltage supply (3.3 V or 1.8 V).

•

The user should ensure that only one of the two power sources is connected: either the

USB connector or the power supply source.

•

Another concern is the voltage drop out of the ammeter. When set to a low-current

range for measuring static power (stop, standby), there is usually a notable drop across

the ammeter due to its impedance. This can interfere with voltage-sensitive case (1.8 V

measurements), and often a power-down reset will occur. This can be avoided by

increasing the power supply voltage output or using regulation techniques relative to

the VDD input to the device.

AN4365 Fiches technique(PDF) 23 Page - STMicroelectronics