Integration Manual

SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R13 System description Page 20 of 119
Figure 5 shows an example of the module current consumption profile versus time in 2G single-slot.
Time
[ms]
RX
slot
unused
slot
unused
slot
TX
slot
unused
slot
unused
slot
M ON
slot
unused
slot
RX
slot
unused
slot
unused
slot
TX
slot
unused
slot
unused
slot
M ON
slot
unused
slot
GSM fram e
4.615 ms
(1 f ram e = 8 slot s)
Current [A]
200 m A
60-120 m A
190 0 m A
Peak current depends
on TX power and
act ual ant enna load
GSM f ram e
4.615 m s
(1 fram e = 8 slot s)
1.5
1.0
0.5
0.0
2.0
60 -120 m A
10-40 mA
Figure 5: VCC current consumption profile versus time during a GSM call (1 TX slot, 1 RX slot)
Figure 6 illustrates the VCC voltage profile versus time during a 2G single-slot call, according to the related VCC current
consumption profile described in Figure 5.
Time
undershoot
overshoot
ripple
drop
Volt age
3.8 V
(t yp)
RX
slot
unused
slot
unused
slot
TX
slot
unused
slot
unused
slot
M ON
slot
unused
slot
RX
slot
unused
slot
unused
slot
TX
slot
unused
slot
unused
slot
M ON
slot
unused
slot
GSM fram e
4.615 m s
(1 fram e = 8 slot s)
GSM fram e
4.615 ms
(1 fram e = 8 slot s)
Figure 6: Description of the 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 network conditions, which set the peak current consumption. But
according to GPRS specifications, the maximum transmitted RF power is reduced if more than one slot is used to transmit,
so the maximum peak of current is not as high as it can be in the case of a GSM call.
If the module transmits in GPRS multi-slot class 12, in 850 or 900 MHz bands, at maximum RF power level, the
consumption can reach a quite a high peak but lower than the one achievable in 2G single-slot mode. This happens for
2.308 ms (width of the 4 Tx slots/bursts) in the case of multi-slot class 12, with a periodicity of 4.615 ms (width of 1 frame
= 8 slots/bursts), so with a 1/2 duty cycle, according to GSM TDMA.
If the module is in GPRS connected mode in the 1800 or 1900 MHz bands, consumption figures are lower than in the 850
or 900 MHz band because of the 3GPP Tx power specifications.