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Smart Module Series
SA800U-WF Hardware Design
SA800U-WF_Hardware_Design 39 / 106
The following figure shows the structure of the power supply.
Module
VBAT
VBAT
C1
100
μ
F
+
C2
100 nF
C3
33 pF
C4
10 pF
D1
Figure 4: Star Structure of Power Supply
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
TPS54428DDAR
U1
VBAT
10
μ
F
C8
22
μ
F
C9
100 nF
R2
120K
27K
R3
22
μ
F
10K
1 %
1 %
EN
100 nF
C3
R1
G
N
D
G
N
D
S
S
VREG5
C7
22
μ
F
VFB
IN
VBST
SW
L1
3.3
μ
H
1
μ
F
8 nF
100 nF
C4
C5
C6
Figure 5: Reference Circuit of Power Supply