Chapter 2: Hardware Interface Description
January 1, 2006 Module Hardware Description 11
It is recommended that the voltage drops during a transmit burst will not exceed 300mV,
measured on the G24 interface connector. In any case, the G24 supply input must not drop below
the minimum operating level during a transmit burst. Dropping below the minimum operating
level may result in a low voltage detection, which will initiate an automatic power-off.
To minimize the losses and transients on the power supply lines, it is recommended to follow
these guidelines:
• Use a 1000 uF, or greater, low ESR capacitor on the G24 supply inputs. The capacitor should
be located as near to the G24 interface connector as possible.
• Use low impedance power source, cabling and board routing.
• Use cabling and routing as short as possible.
• Filter the G24 supply lines using filtering capacitors, as described in Table 2-3.
Power Consumption
Table 2-4 specifies typical G24 current consumption ratings in various operating modes. The
current ratings refer to the overall G24 current consumption over the VCC supply.
Measurements were taken under the following conditions:
• VCC = 3.6 V
• Operating temperature 25°C
• Registered to a GSM network
The actual current ratings may vary from the listed values due to changes in the module's
operating and environment conditions. This includes temperature, power supply level and
application interface settings
.
Table 2-3:
Recommended Power Supply Filtering
Capacitor Usage Description
1000 uF GSM Transmit current
serge
Minimizes power supply
losses during transmit
bursts.
Use maximum possible
value.
10 nF, 100 nF Digital switching noise
Filters digital logic noises
from clocks and data sources.
8.2 pF, 10 pF 1800/1900 MHz GSM
bands
Filters transmission EMI.
33 pF, 39 pF 850/900 MHz GSM
bands
Filters transmission EMI.
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