nRF52832 Current Measurements

[zeb]

Hello,

We recently received an eval kit the the nRF52832, but we were told not to take current measurements with this version. This presents a problem since we are evaluating this chip and need to have a better understanding of the current draws. Could you provide the average current during Advertise and Connect at 0dBm and the sleep currents with RAM retention?

Thanks, Zeb

[Stian Røed Hafskjold]

I assume you have the preview dev. kit with the preview chip version. The DK has more components than just the chip and the reference design, which leads to a higher chance of error. You can easily modify the DK so that only the chip with the ref design draws current. Take a look at the DK schematic: www.nordicsemi.com/.../62078460

The problem is not the DK itself, but how to do the measurements properly. The way the nRF52 power supply works is by rapidly charging a capacitor which will result in a high frequency spike, which some (most?) measurement tools are not able to measure. The solution is to filter out the spike with a regular RC filter.

There is also this errata when using DCDC mode: infocenter.nordicsemi.com/index.jsp, which applies to the preview version of the chip.

You can read more about measuring the chip here in Øyvind's answer: devzone.nordicsemi.com/.../

If you want to look at the average current consumption regarding radio transmission, CPU processing and sleep, take a look at chapter 21.3, 8.2 and 16.20.1 respectively in the nrf52832 product specification: infocenter.nordicsemi.com/.../nrf52832_ps.html

EDIT 01.12.15

We have posted a series of tutorials about measuring current on the nRF52:

devzone.nordicsemi.com/.../

devzone.nordicsemi.com/.../

devzone.nordicsemi.com/.../

[zeb]

Hello Stian,

Thanks for looking into this. The way we have measured the advertise and connect currents in the past is by using amplified differential probes with an oscilloscope and measuring the voltage over low value resistor in series with the power supply. We then capture an entire advertise / connect event and average the current during that time. These are the numbers I'm looking for. After that we use those numbers in combination with total advertise / connect time, depending on which type of device we are talking to, and plug that into our power budget.

We are wary to run this testing as 1) there is errata out there that suggests the numbers may be incorrect and 2) I'm not sure we have the proper hardware to run this test anyway. Would it be possible to provide numbers for the average current draw of a connect/advertise event and the duration of each event? Also to confirm the RAM retention sleep current draw, with 40nA/4k and 64k RAM that yields 640nA sleep + 1.2uA base = 1.84uA, is there anything I'm missing there?

[Stian Røed Hafskjold]

I will look into this. Probably do some measurements and post them here so you can have a look.