Integration Manual

Table Of Contents
TOBY-L3 series - System Integration Manual
TSD-19090601 - R13 System Integration Manual Page 27 of 143
Figure 4 shows an example of the module current consumption profile versus time in 2G single-slot mode.
Time
[ms]
RX
slot
unused
slot
unused
slot
TX
slot
unused
slot
unused
slot
MON
slot
unused
slot
RX
slot
unused
slot
unused
slot
TX
slot
unused
slot
unused
slot
MON
slot
unused
slot
GSM frame
4.615 ms
(1 frame = 8 slot s)
Current [A]
200 mA
60-120 mA
1900 mA
Peak current
depends on TX
power and actual
ant enna load
GSM frame
4.615 ms
(1 frame = 8 slot s)
60-120 m A
10 -40 mA
0.0
1.5
1.0
0.5
2.0
2.5
Figure 4: VCC current consumption profile versus time during a 2G single-slot call (1 TX slot, 1 RX slot)
Figure 5 illustrates VCC voltage profile versus time during a 2G single-slot call, according to the relative
VCC current consumption profile illustrated in Figure 4.
Time [ms]
undershoot
overshoot
ripple
drop
Voltage [mV]
3.8 V
(t yp)
RX
slot
unused
slot
unused
slot
TX
slot
unused
slot
unused
slot
MON
slot
unused
slot
RX
slot
unused
slot
unused
slot
TX
slot
unused
slot
unused
slot
MON
slot
unused
slot
GSM frame
4.615 m s
(1 frame = 8 slot s)
GSM frame
4.615 m s
(1 frame = 8 slot s)
Figure 5: VCC voltage profile versus time during a 2G single-slot call (1 TX slot, 1 RX slot)
When a GPRS connection is established, more than one slot can be used to transmit and/or more than one
slot can be used to receive. The transmitted power depends on the network conditions, which set the peak
current consumption, but following the 3GPP specifications, the maximum Tx RF power is reduced if more
than one slot is used to transmit, so the maximum peak of current is not as high as can be the case with a
2G single-slot call.
If the module transmits in GPRS class 12 in the 850 or 900 MHz bands, at the maximum RF power control
level, the current consumption can reach a quite high peak but lower than the one achievable in 2G single-
slot mode. This happens for 2.307 ms (width of the 4 transmit slots/bursts) with a periodicity of 4.615 ms
(width of 1 frame = 8 slots/bursts), so with a 1/2 duty cycle, according to 2G TDMA.
If the module is in GPRS connected mode in the 1800 or 1900 MHz bands, the current consumption figures
are quite less high than the one in the low bands, due to 3GPP transmitter output power specifications.