Integration Manual

Table Of Contents
TOBY-L3 series - System Integration Manual
TSD-19090601 - R13 System Integration Manual Page 29 of 143
It must be noted that the actual current consumption of the module in 3G connected mode depends also
on the specific concurrent activities performed by the integrated CPU, beside the actual Tx power and
antenna load.
Time
[ms]
3G frame
10 ms
(1 frame = 15 slots)
Current [mA]
Current consumption value
depends on TX power and
actual antenna load
170 mA
1 slot
666 µs
850 mA
0
300
200
100
500
400
600
700
Figure 7: VCC current consumption profile versus time during a 3G connection (TX and RX continuously enabled)
1.5.1.4 VCC current consumption in LTE connected mode
During an LTE connection, the module can transmit and receive continuously due to the Frequency Division
Duplex (FDD) mode of operation used in LTE radio access technology.
The current consumption depends on output RF power, which is always regulated by the network (the
current base station) sending power control commands to the module. These power control commands are
logically divided into a slot of 0.5 ms (time length of one Resource Block), thus the rate of power change
can reach a maximum rate of 2 kHz.
The current consumption profile is similar to that in 3G radio access technology. Unlike the 2G connection
mode, which uses the TDMA mode of operation, there are no high current peaks since transmission and
reception are continuously enabled in FDD.
In the worst case scenario, corresponding to a continuous transmission and reception at maximum output
power (approximately 250 mW or 24 dBm), the average current drawn by the module at the VCC pins is
considerable. At the lowest output RF power (approximately 0.1 µW or 40 dBm), the current drawn by the
internal power amplifier is greatly reduced and the total current drawn by the module at the VCC pins is
due to baseband processing and transceiver activity.
Figure 8 shows an example of the module current consumption profile versus time in LTE connected mode.