N720 Hardware User Guide
Copyright © Neoway Technology Co., Ltd 15
The reference design of the VRTC power supply is shown as below:
Figure 2-3 Capacitors used for the power supply
N720
Close to the module
D1
C1 C2 C3 C4 C5
VBAT
Test point
I_max
Power supply
In Figure 2-3, use TVS at D1 to enhance the performance of the module during a burst. SMF5.0AG
(Vrwm=5 V&Pppm=200 W) 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 2-4 if a 5 V power supply is used.
MIC29302WU in Figure 2-4 is an LDO and outputs a maximum current of 3 A to ensure the performance
of the module.
Figure 2-4 Reference design of power supply control
VCC_IN_5V
VBAT
100 uF
TAN
0.1 uF
TVS
5V
10 uF
470uF
TAN
10K
4.75K
VOUT
MIC29302WU
EN
VIN ADJ
0.1 uF
100pF
33pF
PWR_EN
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