Reference Design For Power Supply - Quectel Smart Module Series Hardware Design

The following figure shows the structure of the power supply.
VBAT

3.4.3. Reference Design for Power Supply

The power design for the module is important, as the performance of module largely depends on the
power source. The power supply of SA800U-WF should be able to provide sufficient current of at least
3 A. By default, it is recommended to use a battery to supply power for the module. If battery is not used, it
is recommended to use a regulator for the module. If the voltage difference between the input and output
is not too high, it is suggested to use an LDO to supply power for the module. If there is a big voltage
difference between the input source and the desired output (VBAT), a buck converter is preferred to be
used as the power supply.
The following figure shows a reference design for +12 V input power source which adopts a buck
converter (TPS54428DDAR) from TI. The typical output voltage is 3.8 V and the maximum rated current is
5.3 A.
DC_IN
C1 C2
22 μF 10 μF
SA800U-WF_Hardware_Design
+
C2
C1
D1
100 μF
100 nF
Figure 4: Star Structure of Power Supply
TPS54428DDAR
IN
R1
10K
C3
EN
100 nF
VREG5
C4
1 μF
8 nF
C5
Figure 5: Reference Circuit of Power Supply
VBAT
C3 C4
10 pF
33 pF
U1
L1
3.3 μH
SW
R2
VBST
120K
1 %
VFB
R3
27K
1 %
Smart Module Series
SA800U-WF Hardware Design
Module
VBAT
C6
100 nF
C7 C8 C9
22 μF 22 μF
100 nF
39 / 106