Application Interface; Power Supply - SIM Tech SIMCom SIM800H Hardware Design

4. Application Interface

4.1. Power Supply

The power supply range of SIM800H 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.
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 SIM800H 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 designed output for the power
supply is 4.1V, thus a linear regulator can be used.
DC INPUT
+
C101 C102
100uF
1uF
SIM800H _Hardware Design_V2.03
VBAT
C
C
33pF 10pF
A
B
Figure 5: Reference circuit of the VBAT input
Part number
MMSZ5231BT1G
PZ3D4V2H
MMSZ4689-V
CDZ55C5V1SM
U101 MIC29302
2
Vout
Vin
1
On/Off
FB
3
PWR_CTRL
Figure 6: Reference circuit of the LDO power supply
5.1V
500mW
Power(watts)
500mW
500mW
500mW
500mW
4
5
R101
+
C103
100K
330uF
R102
43K
20
Smart Machine Smart Decision
Packages
SOD123
SOD323
SOD123
0805
VBAT
R103
C104
470R
100nF
2016-10-10