Current measurements accuracy with Power Profiler Kit 2

[SimonD]

Hello everyone,

I am working on a low consumption product and to optimize it I was using the PPKII to analyze my tuning.

I had strange observations so that I decided to do a very simple setup to compare my multimeter and the PPKII.

The setup is easy : a 440,8kΩ resistance in serie with an ampere meter and the PPKII. A battery of 3,78V has been used to ensure stability in the alimentation. Electric scheme linked.

I was attempting to read a 3,78V / 440,8kΩ = 0,0086 mA = 8,6 µA.

On my multimeter ref UNI-T UT139C I have 8,7µA which is good.

On the PPKII I have 0,61 µA ! Where could come such a difference ? I join the ppk file to my message if someone wants to open it and see that it last a few mili seconds before stabilizing to 0,61 µA.

Thank you in advance for your help !

Best regards,

Simon

Impression Schématique.pdf

test_resistance_440kohms.ppk

[Håkon Alseth]

Hi,

 

a 440,8kΩ resistance in serie with an ampere meter and the PPKII.

The PPK2 is not a true multimeter (ie. cannot measure negative currents, etc).

Try measuring with the PPK2 in series on the positive side, not the negative side of the resistor.

 

Kind regards,

Håkon

[SimonD]

Hi,

Thank you for your anwer ! It works well know. But could you explain to me why it has to be connected in that way instead of the other ? I would like to understand well to be sure of what I do in more complex cases....

Best regards,

Simon

[Håkon Alseth]

Hi Simon,

 

SimonD said:

But could you explain to me why it has to be connected in that way instead of the other ?

The internal circuitry inside the PPK2 needs a positive bias in order to successfully/accurately measure the current.

 

Kind regards,

Håkon

[SimonD]

Hi Hâkon,

Tank you for your answers !

To be sure that I do things right, could you confirm that if I put the ppk2 on the orange wires (cf joint schema) I will be able to measure the consumption of the different parts of my system. Of course, I let the GND of the ppk2 connected to the GND of the circuit.

I am working on an embedded project, powered by a battery. And I have 2 parts, one analog and one digital that is composed with a microcontroleur and an IMU.

Thank you in advance for your advices,

Best regards,

Simon

4010.schema.pdf

[Håkon Alseth]

Hi,

 

SimonD said:

To be sure that I do things right, could you confirm that if I put the ppk2 on the orange wires (cf joint schema) I will be able to measure the consumption of the different parts of my system. Of course, I let the GND of the ppk2 connected to the GND of the circuit.

Yes, that is correct. I assume you want to use it as an ampere-meter, and not a source meter?

In case of ampere meter operation, you can choose to measure both or individually, depending on where you break the connection.

 

Kind regards,

Håkon

[SimonD]

Hi,

Yes it's exact, depending where I break connection I measure multiple component's consumption or only specific one alone.

Thank you for your help,

Best regards,
Simon