Hey all, I have been working on some custom boards using nRF52810-CAAA chips. I use SDK version 15.2. I had some previous issues with sleep currents as seen here, but I resolved them. I have made many versions of custom PCBs, and since resolving my previous issues they have all been great. I get between 2-2.5uA current in System ON sleep mode. However, I just received some boards and they have a strange sleep behaviour as seen in the following nRF Connect power analysis screenshot:
At marker #1, sleep current is appr. 3uA. This is immediately after the device is powered on. The current between advertising spikes slowly increases to 104uA by marker #2, and then even higher to 140uA by marker #3. The current then decreases a little bit by marker #4, to about 70uA. After market #4, current draw remains at around 60-70uA. Below is an MP4 of me scrolling through the various "phases" of sleep current draw changes.
Does anybody have ideas about whether this is a software related issue or a hardware related issue? I'm using the same firmware as I have on previous boards, so this leads me to think it is hardware related. If so, does anyone have ideas about what could cause such a strange sleep draw current like this? I am using various ICs on the board, but they all have enable/disable inputs and in the above screenshots, all of the ICs are in disabled "OFF" mode. My other boards use similar ICs, and setting them to disabled "OFF" mode results in practically no measurable current draw.
The other strange thing is that this behaviour is predictable. Every time I power cycle the device, the same exact current draw pattern is seen. The little "hump" in current draw from 3uA --> 100uA --> 140uA --> 67uA occurs, with the same time duration. I can also advertise, connect to the device, then disconnect which causes advertising to start again, and the same sleep current draw is again observed every time. No matter what I do, this happens when the device enters advertising. When I connect to the device and start reading data from some sensors that are within my custom board, the sleep current snaps down to expected 2-2.5uA values. Stop reading data, start advertising again, and boom the weird sleep current draw is back again.
