EGS5 Hardware Interface Description
3.2 Power Supply
75
EGS5_HD_v02.004
Page 26 of 123
2012-02-09
Confidential / Released
3.2
Power Supply
EGS5 needs to be connected to a power supply at the SMT application interface (3 lines each
BATT+ and GND).
The power supply of EGS5 has to be a single voltage source at BATT+. It must be able to pro-
vide the peak current during the uplink transmission.
All the key functions for supplying power to the device are handled by the power management
section of the analog controller. This IC provides the following features:
•
Stabilizes
the supply voltages for the GSM baseband using low drop linear voltage regula-
tors and a DC-DC step down switching regulator.
•
Switches the module's power voltages for the power-up and -down procedures.
•
Delivers, across the VEXT line, a regulated voltage for an external application. This voltage
is not available in Power-down mode.
•
SIM switch to provide SIM power supply.
3.2.1
Minimizing Power Losses
When designing the power supply for your application please pay specific attention to power
losses. Ensure that the input voltage V
BATT+
never drops below 3.2V on the EGS5 board, not
even in a transmit burst where current consumption can rise to typical peaks of 1.6A. It should
be noted that EGS5 switches off when exceeding these limits. Any voltage drops that may oc-
cur in a transmit burst should not exceed 400mV.
The measurement network monitors outburst and inburst values. The drop is the difference of
both values. The maximum drop (Dmax) since the last start of the module will be saved. In IDLE
and SLEEP mode, the module switches off if the minimum battery voltage (V
batt
min) is reached.
Example:
V
I
min = 3.2V
Dmax = 0.4V
V
batt
min = V
I
min + Dmax
V
batt
min = 3.2V + 0.4V = 3.6V
Figure 3:
Power supply limits during transmit burst
