Hello, I’m using the XIAO nRF52840 Sense along with the XIAO Expansion Board, developing firmware using Zephyr RTOS for low-power BLE applications running on battery.
I’ve successfully reduced sleep current on the nRF52840 Sense board alone from ~730µA down to ~10µA by disabling the QSPI flash. However, when I connect the board to the XIAO Expansion Board and power it only via the 3.3V pin using the PPK2 (no USB-C connected), the sleep current jumps to around 1mA.
I am not sure where this extra consumption might be coming from exactly. Is this expected due to components on the expansion board, or is there a way to reduce this further and to what degree? Has anyone else managed to achieve lower power consumption with the expansion board connected?
SO check out the Threads by our Power Ninja on here @msfujino go look at those threads (3) you will be able to do all kinds of power saving tricks he has discovered. The extra 1ma. may be the onboard battery PMIC, you can look at the schematic from the wiki page and see your power paths. It should help with your endeavor.
You are very close, with the right settings you can get single digit >5uA Talk about sipping power… LOL the Nrf 52840 does a great low power job. Check also the online battery life calculator to get some inciite on size and duration.
The sleep current may decrease a little more. The following link may be helpful.
The expansion board has many components that cannot be turned off, so it may be difficult to reduce the current.
Talk about sipping power… LOL the Nrf 52840 does a great low power job. Check also the online 
PJ 