N1_Hardware_User_Guide
Copyright © Neoway Technology Co., Ltd
17
3 Power Supply Interfaces
3.1 Power Supply
VBAT is the power supply pin of the module. Its input voltage ranges from 3.5 V to 4.2V and the
preferable value is 3.9V. In addition to digital baseband and analogue baseband, it supplies power to RF
power amplifier. The performance of the VBAT power supply is a critical path to module's performance
and stability. The peak input current at the VBAT pin can be up to 2 A when the signal is poor and the
module works at the maximum transmitting power. The voltage will encounter a drop in such a situation.
The module might restart if the voltage drops lower than 3.5 V.
Figure 3-1 shows the reference design of the VBAT power supply.
Figure 3-1
Capacitors used for the power supply
N1
Close to the module
D1 C1 C2 C3
C4 C5
VBAT
Test point
I_max
Power supply
In Figure 3-1, use TVS at D1 to enhance the performance of the module during a burst. SMF5.0AG
(Vrwm=5V&Pppm=200W) is recommended. A large bypass tantalum capacitor (220 μF or 100 μF) or
aluminum capacitor (470 μF or 1000 μF) is expected at C1 to reduce voltage drops during bursts together
with C2 (10 μF ceramics capacitor). In addition, add 0.1 μF, 100 pF, and 33 pF filter capacitors to enhance
the stability of the power supply.
The module might fail to reset or power on/off in remote or unattended applications, or in an environment
with great electromagnetic interference (EMI). A controllable power supply is preferable if used in harsh
conditions. Use the EN pin on the LDO or DC/DC chipset to control the switch of the power supply as
shown in Figure 3-2 if a 5V power supply is used.
MIC29302WU in Figure 3-2 is an LDO and outputs a maximum current of 3 A current to ensure the
performance of the module.
