Integration Manual

Table Of Contents
TOBY-L3 series - System Integration Manual
TSD-19090601 - R13 System Integration Manual Page 28 of 143
Figure 6 reports the current consumption profiles in GPRS class 12 connected mode, in the 850 or 900 MHz
bands, with 4 slots used to transmit and 1 slot used to receive.
It must be noted that the actual current consumption of the module in 2G connected mode depends also
on the specific concurrent activities performed by the integrated CPU, beside the actual Tx power and
antenna load.
Time
[ms]
RX
slot
unused
slot
TX
slot
TX
slot
TX
slot
TX
slot
MON
slot
unused
slot
RX
slot
unused
slot
TX
slot
TX
slot
TX
slot
TX
slot
MON
slot
unused
slot
GSM frame
4.615 ms
(1 fram e = 8 slot s)
Current [A]
200mA
60-130mA
Peak current depends
on TX power and act ual
ant enna load
GSM frame
4.615 ms
(1 frame = 8 slots)
1600 mA
0.0
1.5
1.0
0.5
2.0
2.5
Figure 6: VCC current consumption profile during a 2G GPRS/EDGE multi-slot connection (4 TX slots, 1 RX slot)
For EDGE connections, the VCC current consumption profile is very similar to the GPRS current profile, so
the image shown in Figure 6, representing the current consumption profile in GPRS class 12 connected
mode, is valid for the EDGE class 12 connected mode as well.
1.5.1.3 VCC current consumption in 3G connected mode
During a 3G connection, the module can transmit and receive continuously due to the Frequency Division
Duplex (FDD) mode of operation with the Wideband Code Division Multiple Access (WCDMA).
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 666 µs, so the rate of power change can reach a maximum rate of 1.5 kHz.
There are no high current peaks as in the 2G connection, since transmission and reception are continuously
enabled due to FDD WCDMA implemented in the 3G that differs from the TDMA implemented in the 2G
case.
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 0.01 µW or 50 dBm), the current drawn by
the internal power amplifier is strongly reduced. The total current drawn by the module at the VCC pins is
due to baseband processing and transceiver activity.
Figure 7 shows an example of the current consumption profile of the module in 3G WCDMA/DC-HSPA+
continuous transmission mode.