Fibocom MG661-EU - Control Interfaces; Power-on

3 Application Interfaces
27
It is recommended to reserve the TVS tube position for the VBAT power supply.
Recommended model: ESDH4V5P1/ESD5651N.
PCB Design
To reduce the equivalent impedance of the VBAT routing, the routing from the external power
supply to VBAT is required to be as short and wide as possible (it is recommended that the
routing width of VBAT should be at least 2 mm/2A to ensure sufficient power supply capacity).
The capacitors with a small capacitance should be placed close to the module, and the
ground plane of the power supply part should be as complete as possible.
Power supply layout and routing are far away from interference sources such as antennas.
3.1.3 Power Output
The power output interface of the module is described in the following table.
Table 25. Module power interface
Pin No.
Pin Name
I/O
Description
DC Parameter
Minimum
Value (V)
Typical
Value
(V)
Maximum
Value (V)
24
VDD_EXT
PO
Digital level 1.8V,
100mA
1.74
1.8
1.85
3.2 Control Interfaces
3.2.1 Power-on
Schematic Diagram Design
The startup sequence of the module is shown in the following figure.