Power Profile Kit II measures 1.5microAmps when disconnected

RE: Power Profile Kit II measures 1.5microAmps when disconnected

Kazi Afroza Sultana — Thu, 27 Jan 2022 09:48:45 GMT

Hello Vladimir,

The second kit seems working fine. Have you tired the first kit in Ampere Meter mode ? You can try this with the first kit and see if you would get proper value like zero.

It is strange when both are going through the same calibration and same components; but first one is not functioning accordingly. I would like to know the device id of Both PPK2s so our team can find if there is any bug that makes deviation between two.

And also if you want , you can do an RMA on the first PPK2 that you have. I think we can replace that for you if the distributor has not done already.

Thanks.

Best Regards,

Kazi Afroza Sultana

RE: Power Profile Kit II measures 1.5microAmps when disconnected

vofitserov — Thu, 27 Jan 2022 00:34:56 GMT

I've got another PPK2 from the DigiKey today. Measured disconnected circuit, got 0.1uA (broken kit was showing 1.5uA). I also measured same 101.2K resistor and got expected 7.8uA. The first kit just has some soft of the problem.

RE: Power Profile Kit II measures 1.5microAmps when disconnected

Kazi Afroza Sultana — Tue, 25 Jan 2022 06:13:21 GMT

Ok. Let us know your findings with the new PPK.

Regards

Kazi Afroza Sultana

RE: Power Profile Kit II measures 1.5microAmps when disconnected

vofitserov — Mon, 24 Jan 2022 20:02:07 GMT

I've measured 100K resistor with digital multimeter (EX330 that claims 0.50% accuracy), got 101.2K. I expected that without the circuit the current should be measured as 0uA but board consistently shows 1.3uA. I could be looking at the ghosts but if I substract 1.3uA from 9.1uA measured at 101.2K resistor I got expected 7.8uA (101.2K over 0.8V). I am speculating, but there is something in the my PPK that leaks about 1.3uA that adds to the measurement. I've asked distributor to send me another instance, I'll check in a few days and report what I find.

RE: Power Profile Kit II measures 1.5microAmps when disconnected

Kazi Afroza Sultana — Mon, 24 Jan 2022 11:08:17 GMT

Hello Vladimir,

Thanks for your query. Sorry for the late reply as your query arrived in weekend.

Can you please share your measurement set up (photo or drawing)? You are talking about 800 mV supply; is this from the PPK or separate supply?

To get a true zero, we have to consider other factors like environmental noise, noise from the USB as well as the consideration of kit. It has to be make sure that the working environment is ESD safe, USB power supply is isolated from main and proper working of shielded USB cables. It should not be source the DUT rather using a proper power supply which can offer better accuracy and noise suppression. I think Andrew pointed out right thing.

Another issues have also impact on this value - the way you measure the resistor; the type of multimeter is used. Measurements can be varied based on these parameters.

Thanks.

Best Regards,

Kazi Afroza Sultana

RE: Power Profile Kit II measures 1.5microAmps when disconnected

Andrew Lentvorski — Mon, 24 Jan 2022 04:47:36 GMT

Why not? Have you checked the specs on the Power Profiler Kit II?

9 microAmp is right about what would be measured with a 100K resistor with a 10% tolerance is the tolerance is on the low side. A 20% tolerance is easily in range.

Resolution of the board at the requested range is 0.2uA so that looks correct.

Accuracy is +/- 10%. Offset is 2%.

101.2K resistors don't exist, so you are citing a measurement that *also* has it's own inaccuracy.

If you want accurate measurements near instrument limits, you need to understand the limitations of your instruments.

RE: Power Profile Kit II measures 1.5microAmps when disconnected

vofitserov — Mon, 24 Jan 2022 01:50:20 GMT

I've connected 101.2K resistor with 800mv supply, got 9.09 microAmp (expected 7.9microAmps) with noise from 9.0 to 9.2 microAmp. This can't be right.

RE: Power Profile Kit II measures 1.5microAmps when disconnected

Andrew Lentvorski — Mon, 24 Jan 2022 00:12:27 GMT

I presume you mean that your DUT is effectively an "open circuit" when you say "disconnected".

You cannot measure *current* into an open circuit. Measuring current into a short circuit is also problematic. This is not a voltmeter.

If you wish to do a quick sanity check, put a 10 Megaohm or 100 Megaohm resistor as the DUT. This gives you a complete circuit that you can check the current on.

Hope this helps.