How to Measure Power Consumed by iMX6Q Sabrelite

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How to Measure Power Consumed by iMX6Q Sabrelite

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lucasmahieu
Contributor III

Hey,

I need to measure the power consumed by the 4 CORES of the iMX6Q Sabre Lite.

I found on web the AN4509.pdf which deals with the Power consumed by a SabreSD,

I would like to get same information which are explained in this document.

More exactly i think the power I need is from : VDDARM_IN (CPU Power)

On the Sabre SD it is available on "R27 for VDDCORE" according to the AN4509.

I really need this information, so It would be GREAT someone find any solution.

Best Regards

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lucasmahieu
Contributor III

Hey Artur,

thanks a lot for your response !

It is a good idea but how can I measure

" the average current in series with the L11 inductor "

and the

"the current in series with the L1 inductor"

This is the difficulty ... because measuring a voltage is easy, but nor current.

Do you have some ideas ?

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art
NXP TechSupport
NXP TechSupport

You may try to desolder the inductors, then solder only one side, on another side, connect the amperemeter between the inductor's pad and the PCB pad.

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art
NXP TechSupport
NXP TechSupport

You can try the following approach.

First, measure the total current consumption on the VCC_1P2V power rail in some comfortable point, i.e. measure the average current in series with the L11 inductor. Then, measure the current in series with the L1 inductor. Since the VCC_1P2V power rail supplies only the VDD_ARM_IN and VDD_SOC_IN power inputs of the processor, you can easily calculate the VDD_ARM_IN current by subtracting the measured VDD_SOC_IN current (measured at L1) from the total VCC_1P2V rail current (measured at L11). Then, you can measure the voltage on C4 or C5 and then easily calculate the electric power, consumed by the CPU cores through the VDD_ARM_IN power rail.


Have a great day,
Artur

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lucasmahieu
Contributor III

This manuel is awesome, I didn't have it ...

Thanks a lot for this.

So, If i want to know how many power the CPUs consume:

I can measure the voltage on the output of U11 which will be constant, typically 1,2v, right ?

But if so, I have to get the courant consumed by the imx6q ?

And the power consumed will be P(t) = Courant(t) * Voltage(t).

Am I right ?

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gary_bisson
Senior Contributor III

Hi,

Yes you are right the voltage will stay at 1.2V whereas the current will vary. To be honest it won't be easy to measure the current just for those lines.

Usually customers measure the current at the 5V input directly but that gives the total board consumption only.

Regards,

Gary

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lucasmahieu
Contributor III

Good, so i have understand,

Yes, this is really not a simple operation ...

But in my case, i really need the CPUs consumption, so the board consumption is really to far from what a need due to the consumption of BUS, memory, peripherals (USB, HDMI, ...) and so one ...

Thanks for your time, i will try to find a way to got this information by the best way.

Regards

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gary_bisson
Senior Contributor III

Hi,

First of all I'd like to clarify that the SABRE SDB is using an external PMIC whereas the Sabre-Lite is not. Therefore the application note you mention might not apply on this board.

Then, I suggest you download the board schematics in order to see the different power supplies:

https://boundarydevices.com/product/sabre-lite-imx6-sbc/

Regarding VDDARM, I suggest you look at the output of U11. As for VDDSoC, you can probe it on R3.

Hope this helps.

Regards,

Gary

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lucasmahieu
Contributor III

Thanks a lot Gary,

According to the schematics,

U11 has for input : 5v

And give VCC_1P2V to the imx6 VDDARM_IN_i,  i=[1..8]

I don't understand something... How U11 can give the right power ?

Because the imx6 have to scale the cpu power input according to its frequency, right ?

Does this task is made by U11 ? or into the Imx6q bloc ?

Because my aim is to get the power consumed by all 4 cores.

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gary_bisson
Senior Contributor III

Hi Mathieu,

U11 is just a step-down converter which can provide up to 4A but its power use depends on the load you put on the other side of course.

If you look for information on the Dynamic Frequency and Voltage Scaling (DVFS) which is managed in the i.MX6 directly, I suggest you read section 10.4.1.6.1.1 DVFS of the i.MX6DQ Reference Manual.

Regards,

Gary

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