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SIM800_Hardware Design_V1.10 20 2018-08-13
4. Application Interface
4.1. Power Supply
The power supply range of SIM800 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 100µF is strongly recommended.
For the VBAT input, a 100uF Tantalum capacitor (CA low ESR) and a 1uF~10uF Ceramics capacitor CB are
strongly recommended .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 to SIM800 VBAT pins as
possible.
VBAT
5.1V
500mW
C
A
C
B
33pF
10pF
Figure 5: Reference circuit of the VBAT input
Table 5: Recommended Zener diode
Vendor Part number Power(watts) Packages
1 On semi MMSZ5231BT1G 500mW SOD123
2 Prisemi PZ3D4V2H 500mW SOD323
3 Vishay MMSZ4689-V 500mW SOD123
The following figure is the reference design of +5V input power supply. The designed output for the power
supply is 4.1V, thus a linear regulator can be used.
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