User's Manual

Date: 2010/02/04
Version: 1.0
Status: Released
7/22 ACM8068 HW Application Manual V1.0 ©Copyright 2010, AMOD Technology
3. Power Supply Recommendations
3.1 PowerSupplyGeneralities
Power supply design is critical to GSM module applications. The design guides
should be strictly followed to ensure the performance of the module. The VBAT
voltage limits must be at any time: 3.4V <VBAT< 4.5V. The worst condition is
during the burst period transmission, when current consumption is at its highest.
During this period, the VBAT voltage is reduced to the lowest level:
• The output voltage of the power supply drops.
• Voltage drop is present between the power supply output and the GSM module
supply pins (VBAT).
Figure 2: VBAT voltage drop
3.2 VoltageVersusDistance
Depending on the distance between the power supply and the GSM module, behavior
is described as figure 3:
VBAT
Current
Transmit
burst 2A
Transmit
burst 2A
Voltage Drop≦
400mV
Voltage
minimum=3.4V