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FIBOCOM SQ806-W Series Hardware Guide
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3 Application Interface
3.1
Power Supply
The module provides four VBAT pins for connecting to external power supply source. The input range of
power is 3.5V~4.2V and the recommended value is 3.8V. The performance of the power supply such as
its load capacity, ripple etc. will directly affect the operating performance and stability of the module. In
extreme cases, the peak current of the module can reach 2A and if the power supply capacity is
insufficient that VBAT voltage instantaneous drops below 3V, the module may be powered off or restarted.
The VBAT voltage drop is as follows:
Burst Transmit
Burst Transmit
3V
Drop
500mV
VBAT
3.5V
Figure 3-1 VBAT voltage drop
3.1.1
Power Input
External power source supplies the module by VBAT pins. To ensure the instantaneous voltage is no less
than 3V, it is recommended to connect two 220μF tantalum capacitors with low ESR and filter capacitors
of 1uF, 100nF, 39pF and 33pF in parallel to the VBAT input of the module. Besides, the PCB cable of
VBAT should be as short and wide as possible (no narrow than 3mm) and the ground plane of the power
section should be flat. That can reduce the equivalent impedance of the VBAT cable and ensure at
maximum transmit power, significant voltage drop will not occur at high currents.
