Specifications

Smart Machine Smart Decision
SIM5800_Hardware Design_V1.01 22 2018-10-08
5.1V
500mW
33pF
VBAT
GND
C101
C103
100uF
MODULE
D101
C105
100uF
VBAT_RF
Figure 7: VBAT Input reference circuit
In the Figure 7, C101/C105 is 100uF tantalum capacitors of low ESR; 33pF capacitance can effectively remove
high frequency interference; 5.1V/500mW zener diode can prevent the damage of surge on the chip. The
capacitance and zener diodes should be as close to the VBAT pin of the module as possible during PCB layout.
Table 3: Recommended Zener diode model
Vender
Part Number
Power
Pack
1
On semi
MMSZ5231BT1G
500mW
SOD123
3
Prisemi
PZ3D4V2H
500mW
SOD323
4
Vishay
MMSZ4689-V
500mW
SOD123
5
Crownpo
CDZ55C5V1SM
500mW
0805
4.1.1 Power Supply Pins
The VBAT pins are used for power input, and pin 143, 144, 147, 148 should be connected to the power GND.
VRTC pin is the power supply of the RTC circuit in the module.
When designing the power supply in users’ application, pay more attention to the power losses. Ensure that the
input voltage never drop below 2.9V even when current consumption rises to 2A in the transmit burst. If the
power voltage drops below 2.9V, the module may be shut down automatically. The PCB traces from the VBAT
pins to the power supply must be wide enough to decrease voltage drops in the transmit burst. The power IC and
the bypass capacitor should be placed to the module as close as possible.
VBAT
MIN:2.9V
Figure 8: The minimal VBAT voltage requirement at VBAT drop
4.2 Power on/off
Do not open the module when the temperature and voltage limit of the module is exceeded. The module will be
shut down as soon as it detects these inappropriate conditions. In extreme cases such an operation can result in
permanent damage to the module.
4.2.1 Power on