Calculate the maximum power consumption of an Microcontroller

[hioyo]

May I know how to calculate the power consumption of a uC.

Assume it is working at 3.3V and it's 5 GPIO's are connected to 5 LED's .Duty cycle is 50%.

 

[danadakk]

Duty cycle of what ?

You need to know :

1) Clock rates of micro
2) All GPIO loads
3) Code execution effects on micro
4) Micro type
5) Internal micro peripheral loads and power specs.....

This is best done with a DAQ or oscilloscope doing data logging of the whole system.

Designers use datasheet specs for guidelines. Then add external system
power consuming devices to that.

Your question is like how tall is a building in Russia, with no other info
or parameters. Simply unanswerable.


Regards, Dana.

 

[KlausST]

Hi,

I fully agree with Dana.

Additionally it depends on where you measure the current ... and how the LEDs are connected.

Klaus

 

[crutschow]

May I know how to calculate the power consumption of a uC.

Show us the complete circuit will all the part values and signal frequencies.

 

[hioyo]

Duty cycle of what ?

You need to know :

1) Clock rates of micro
2) All GPIO loads
3) Code execution effects on micro
4) Micro type
5) Internal micro peripheral loads and power specs.....

This is best done with a DAQ or oscilloscope doing data logging of the whole system.

Designers use datasheet specs for guidelines. Then add external system
power consuming devices to that.

Your question is like how tall is a building in Russia, with no other info
or parameters. Simply unanswerable.


Regards, Dana.

Hi Dana,

Please don't feel bad .This question is asked in an interview.(Lost my Job,currently searching).
Duty cycle here means LED is on for half the time of PWM.
If you can suggest any material so that I can study will be helpful.

Regards

 

[KlausST]

Hi,

don´t push the effort to someone else.

Since there are countless different options and ways ... it´s better you chose one of your interest.

****
One simple example:
One can measure the microcontroller current at VCC or at GND. Let´s choose to measure it on the VCC side.

Now you have two options to connect a LED to the microcontroller:
* cathode points to microcontroller --> LED current is not seen on microcontroller VCC
* or anode points to microcontroller --> LED current runs through microcontroller VCC

****

Make a simple drawing on your own. And use a colored pen to depict the current flow.

Klaus

 

[danadakk]

Basically if I have a load that I switch on and off, then its power
dissipation is proportional to the time I have it on. Duty cycle
= Ton / (Ton + Toff ). So if I have a 100W light bulb, and I switch
it on and for equal times, then duty cycle = 50%, and the effective
power being consumed over time is 50%.

That concept is used in micros where they service a task, then go to sleep.
So overall power consumed is duty cycle X ( micro power + other loads that
get switched off) + loads that do not get switched off .

https://ww1.microchip.com/downloads/en/Appnotes/90001416a.pdf

Regards, Dana.