User Guide

19／35
3.3 Power Interface
Table 5 lists the definitions of the pins on the power supply interface.
Table 5 Definition of power interfaces
Pin No. Pin Name I/O Description
2, 24, 39 , 41, 52 VBAT PI 3.3~4.2V Power Input
4, 9, 15, 18, 21,
26, 27, 29, 34 ,35,
37, 40, 43, 50
GND Ground
When the M3B module works normally, power is supplied through the VBAT pins. When it works
at EGSM900 mode and transmits current may reach the transient peak value of about 3 A. To make
sure that the voltage does not decrease below 3.3V, a low-dropout (LDO) regulator or switch power
with current output of more than 3 A is recommended for external power supply. Furthermore, it is
recommended that customers add the 1000uF or above energy storage capacitor to connect in
parallel at the power interface of the M3B module. And keep the power device and power cable away
from antenna to avoid EMI interference.
Figure 3 shows the recommended power circuit of M2 module using DC-DC power supply. The
resistance accuracy of R3 and R4 is 1%. The capacitance E1 needs to use high polymer tantalum
capacitor to add the drive capability of pulse current in dialing process.
Figure 3 Recommended Power Circuit of the M3B module
uCloudlink M3B Mini PCIe-C _Hardware Design Guide_V1.0