Power Supply; Power Supply Design - Motorola G24 Developer's Manual

Power Supply

Power Supply
The G24 power supply must be a single external DC voltage source of 3.3V to 4.2V. The power
supply must be able to sustain the voltage level during a GSM transmit burst current serge, which
may reach 2.0A.
The G24 interface connector has 8 contacts for the main power supply, as described in
All these contacts must be used for proper operation.

Power Supply Design

Special care must be taken when designing the power supply of the G24. The single external DC
power source indirectly supplies all the digital and analog interfaces, but also directly supplies the
RF power amplifier (PA). Therefore, any degradation in the power supply performance, due to
losses, noises or transients, will directly affect the G24 performance.
The burst-mode operation of the GSM transmission and reception, draws instantaneous current
surges from the power supply, which causes temporary voltage drops of the power supply level.
The transmission bursts consume the most instantaneous current, and therefore cause the largest
voltage drop. If the voltage drops are not minimized, the frequent voltage fluctuations may
degrade the G24 performance.
Figure 2-2
Figure 2-2: Transmission Power Drops
10
Table 2-2: Power Supply Signals
Pin # Signal Name
1-4 GND
5-8 VCC
illustrates the power supply behavior during GSM transmission.
Module Hardware Description
Description
Main ground connection for G24
module.
DC supply input for G24 module.
V = 3.3 V to 4.2 V
IN
I = 550 mA during multislot
RMS
transmission
I = 2 A during transmit bursts
MAX
Table 2-2.
January 1, 2006