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Measuring current consumption with CR2032 battery as the input

Hi!

I wanted to ask someone who knows more than I, if this setup makes sense, and how I could test my design.

A bit of background: We're developing a custom board which works with an nRF52840 chipset and has some peripherals onboard which server some function. I wanted to test current consumption on my board so I started with an input DC power supply, set the current max and set the voltage to ~3.0V to simulate a CR2032 battery. I ran the test and got the results.
Now, I want to test with an actual CR2032 battery, so I replaced the DC power supply with a CR2032 and got the setup described below.

Now my problem is that my device would either not start at all, or start and shut down after a very very short amount of time (seconds), due to low voltage. This happens with all batteries (even new ones) and the voltage measured on the battery after I take it out reads very low ~2.something V. This repeats whether I have the DMM connected  in parallel or not.

So, I'm assuming there is a huge peak in current consumption which leads to a large drop in battery voltage. The DC supply can handle this, but the battery can not, and so my device shuts down. I'm also assuming the PPK itself - which is connected in series with my DUT, has some voltage drop on it, so my DUT isn't getting the full voltage from the battery.

my questions are:

1. Is my analysis of the cause of the failed measurement reasonable?

2. What is the usual way by which one measures power consumption with devices such as this? Is a DC power supply a reasonable simulation of the behavior of the device with a CR2032 battery?
3. Is a set of measurements with the PPK with a CR2032 battery as input possible? if so, is there a 'proper' way to set this up?

Thanks!

Parents Reply
  • Hi Patrick!
    Thank you for the answer!
    I assumed the PPK was drawing the relevant power it needs (as opposed to the one the DUT draws) from the USB connected to it. I'll look at the specifications to see if I can spot anything mentioning this.

    If what you're saying is correct, then I assume that would mean that one can not use a CR2032 battery as an input voltage into the PPK..

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