Device current consumption
Bluetooth module will consume the most when trying to establish a connection. In addition to connecting, transmitting or receiving, such a device will go through various states, such as standby, processing (full or partially), idle etc.

The different layers of the bluetooth device stack require a certain amount of processing time to remain connected and comply with the protocol's specifications. The
MCU takes time to perform this processing and some current is consumed to do so. Also,
the device might go through the transition states which also consumes current. 

Generally, such a device can have up to 10 states of power consumption:

1 Pre-processing: IC wake-up from sleep and radio setup.

2 Standby+XOramp: No active clock management and Crystal oscillator ramped. This value depends on the type of crystal.

3 Standby: No clock management active. This value depends on the
type of crystal.

4 Pre-to-Tx: Radio turns on for Tx and Rx.

5 Advertise: Tx Radio transmits an advertisement packet. Time is dependent on the amount of transmitted data.

6 Tx-to-Rx: Standard Tx to Rx transition.

7 Listen mode: Rx Radio listens for a packet from the master.

8 Post-processing: BLE protocol stack processes the received packets and
set up for idle timer for the next event.

9 Pre-Idle: Transition from post processing to Pre-idle-to-idle.

10 Pre-idle-to-Idle: Transition for Pre-idle state to Idle state.


More than that, the power management system is highly flexible with functional blocks such as the CPU, radio transceiver and peripherals having separate power state control in addition to the global System ON/OFF modes. In System OFF mode, RAM can be retained and the device state can be changed to System ON through reset or a GPIO signal. In the System ON mode, all functional blocks will be independently in the IDLE or RUN mode depending on the needed functionality. 

Therefore, the power consumption can vary quite a lot, with a peak when establishing connections and with a minimum when the system in mostly in stand-by mode.