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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!

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  • Hi,

    1. Yes. Patrick's answer is correct

    2. The major differences between a battery and a DC power supply is the internal resistance of the battery and discharge rate. The internal resistance can be simulated by placing a resistor in series with the VDD input, and battery discharge by lowering the voltage. If you just want to measure the average power consumption, a DC power supply is usually good enough.

    3. Sorry, no.

Reply
  • Hi,

    1. Yes. Patrick's answer is correct

    2. The major differences between a battery and a DC power supply is the internal resistance of the battery and discharge rate. The internal resistance can be simulated by placing a resistor in series with the VDD input, and battery discharge by lowering the voltage. If you just want to measure the average power consumption, a DC power supply is usually good enough.

    3. Sorry, no.

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