User Guide

GM47/48 Design Guidelines
BA/SEM/MSC 02:0006 Rev PA1 10
3.3 External Supply to Module
Pins Name Description
1, 3, 5, 7, 9, 11 VCC Regulated Power Supply
Connect all of the pins together in the application in order to carry the
current drawn by the module.
3.3.1 Power Supply (VCC)
The VCC supplies the module with external power. Any other voltage
needed is generated internally.
Parameter Mode Limit
Voltage to be applied Nominal 3.6 Volts
Tolerance 3.4 Volts - 4.0 Volts
Maximum voltage drop during
transmit burst
200mV
Over voltages 5.5 Volts
Current Drive capability at TX Full Power < 600 mA (average))
< 2 A (Peak)
GM 47/48 does not have internal capacitance to supply the large
current peaks during GSM transmission. Therefore on burst
transmission the application DC source is responsible for providing the
appropriate current.
Recommendations to the design of power supplies are given in the
following sections.
V1
3.6V
C1
220uF
CF
100uF
Low ESR
CBULK
1000uF
Low ESR
RLINE
100mohm
RRX
120ohm
30mA Load
RTX
1.8ohm
2A Load
J1
577usec
1:8 Duty Cycle
'R
LINE
' represents resistance
of circuit between PSU and
GM47/GM48.
L1
33uH
+
+
+
2 Amp
Vcc
Figure 3.2 - Simplified Power Supply Reference Model