Hi there! I'm totally out of any ideas and I need your valuable help!
My company is targeting to use a ready-solution of nRF5340-based BLE module for an Ultra-low-power BLE product on the market! We have started evaluating Fanstel BT40 and HolyIoT 21069 modules for our goal.
We needed to know how much would be the lowest possible power consumption from the moment of power-on to the first 1 or 2 BLE Tx packets while nRF5340 is working in non-connectable BLE broadcaster.
1. Initially we started with a nRF5340-DK board configured in "nRF-ONLY" mode from an external power source (we use Nordic PPK2 kit to power it and also measure the current consumption). There we've measured average current consumption of 1.4mA from boot until the second successfully sent BLE packet, which is great! Anything under 1.5mA fits great for our use case!
2. Then we've got Fanstel EVM-BT40 kit and we've measured there 1.44mA. A current consumption profile attached. So far, so good!
3. Then we've got a standalone Fanstel BT40 module only and connect to it just minimal wiring - only put it power supply of 1.8V on VDD pad and short-circuit VDDH to VDD as per Nordic recommendations. With 100% absolutely the same code flashed on it we've measured 2.87mA average power consumption which is almost twice than required! 
4. We have even got HolyIoT 21069 nRF5340 module connect it in the same way (just power and VDDH short circuit) and we measure there more or less the same - ~2.7mA
We don't know what hardware-wise we are missing which would be there or the devkits but is not on the standalone modules...
Everywhere (for the 4 experiments) we flash one and a same software!
Any additional capacitors are required or what else would be needed?
Can someone suggest anything to check, any ideas are welcome?!
PS:
As you can see on the diagrams, in the case of Fanstel EVM-BT40 kit there is more noise during boot, but the consumption between BLE Tx packets is lower.
In the case of standalone BT40 module, during boot-up there is less noise, but the consumption is a way higher between the BLE Tx packets.
This is driving me thinking it is something related to enabling DC-DC regulators, which is probably unsuccessful on the standalone Fanstel BT40 module... But why?
