Application Interface; Power Supply - SimCom SIM800C Hardware Design

4. Application Interface

4.1. Power Supply

The power supply range of SIM800C is from 3.4V to 4.4V. Recommended voltage is 4.0V. The transmitting
burst will cause voltage drop and the power supply must be able to provide sufficient current up to 2A. For the
VBAT input, a bypass capacitor (low ESR) such as a 100 µF is strongly recommended.
For the VBAT input, a 100uF Tantalum capacitor (C
strongly recommended. Increase the 33pF and 10pF capacitors can effectively eliminate the high frequency
interference. A 5.1V/500mW Zener diode is strongly recommended, the diode can prevent chip from damaging
by the voltage surge. These capacitors and Zener diode should be placed as close as possible to SIM800C
VBAT pins.
Table 6: Recommended zener diode
Vendor
1 On semi
2 Prisemi
3 Vishay
4 Crownpo
The following figure is the reference design of +5V input power supply. The output power supply is 4.1V, thus a
linear regulator can be used.
D C I N P U T
+
C 101
100uF
If there is a high drop-out between the input and the desired output (VBAT), a DC-DC power supply will be
preferable because of its better efficiency especially with the 2A peak current in burst mode of the module. The
SIM800C_Hardware_Design_V1.02
A
V B A T
C
C
33pF 10pF
A
B
Figure 5: Reference circuit of the VBAT input
Part number
MMSZ5231BT1G
PZ3D4V2H
MMSZ4689-V
CDZ55C5V1SM
U 101 M I C 29302
2
V out
V i n
1
C 102
O n/ O f f
1uF
3
P W R _C T R L
Figure 6: Reference circuit of the LDO power supply
low ESR) and a 1uF~10uF Ceramics capacitor C
5. 1V
500m W
Power(watts)
500mW
500mW
500mW
500mW
4
5
R 101
F B +
C 103
100K
330uF
R 102
43K
17
Smart Machine Smart Decision
B
Packages
SOD123
SOD323
SOD123
0805
V B A T
R 103
C 104
470Ω
100nF
2015-4-27
are