Specifications

Smart Machine Smart Decision
SIM5800_Hardware Design_V1.01 21 2018-10-08
4. Interface Application
4.1 Power Supply
For non-battery applications, if the DC input voltage is +5V and users do not care about the power efficiency, a
high-current low-dropout regulator is recommended. The reference design is shown in Figure 5
Vin
Vout
GND
FB
3
+
PWR_CTRL
R102
R101
VBAT
100K
47K
+
C103
330uF
C104
100nF
U101
MIC29302
5
4
1
2
C101 C102
100uF
1uF
DC INPUT
R103
470R
On/Off
Figure 5: LDO power supply reference circuit
Note: To ensure a proper behavior of the regulator under light load, an extra minimum load (R103 in Figure 5)
is required, because the current SIM5800 consumed is very small in sleep mode and power off mode. For more
details about minimum load, please refer to specification of MIC29302.
To increase power efficiency, the switching mode DC-DC converter is preferable, especially when DC input
voltage is quite high. The reference design is show in Figure 6, and it is recommended to reserve a proper ferrite
bead (FB101 in Figure 6) in series for EMI suppression.
Vin
Vout
FB
U101
1
2
3
4
5
LM2596- ADJ
+
100uH
MBR360
L101
C101
+
C102
D102 C103
R102
R101
FB101
330uF
VBAT
2.2K
1K
100uF
1uF
C104
100nF
270R@100MHz
DC INPUT
PWR_CTRL
GND
On/Off
Figure 6: DC-DC power supply reference circuit
The user can directly power the module with a single lithium battery or use other types of battery, but it should be
noted that its maximum voltage cannot exceed the maximum allowable voltage of the module, otherwise the
module will be damaged.
Note: The module supports charging function. When users use non-rechargeable power supply, they need to
turn off the charging function in the software or connect schottky diodes in the VBAT path to prevent reverse
flow of current into the power supply.
No matter which power supply design is adopted, please refer to the following figure for the design of VBAT pin
of the module.