Neo_M680 GPRS Module Hardware User Guide
Copyright © Neoway Technology Co., Ltd
9
3 Interface Design
3.1
Power Supply and Switch Interfaces
Table 3-1
Power supply and switch interface
Signal
I/O
Function
Remarks
VBAT
P
Main power supply input
3.5 V to 4.3 V (3.9 V is recommended)
VDD_EXT
P
2.8 V power supply output
Loading capability < 50 mA
VRTC
P
RTC power supply input
2.8 V
ON/OFF
DI
On/Off input
Low level pulse can change the On/Off state.
RESET
DI
Module reset input
Reset at low level
Min. 50 ms
100 ms is recommended
3.1.1 Design Requirements
VBAT
is the main power supply of the module. Its input voltage ranges from 3.5 V to 4.3 V and the
preferable value is 3.9V. In addition to digital signals and analog signals, it supplies power for RF power
amplifier
.
The performance of the VBAT power supply is a critical path to module's performance and stability. The
peak input current at the VBAT pin can be up to 2 A when the signal is weak and the module works at the
maximum transmitting power. The voltage will encounter a drop in such a situation. The module might
restart if the voltage drops lower than 3.5 V.
Figure 3-1
Current peaks and voltage drops
Keep above 3.5 V
Keep above 3.5 V
3.5 V
3.5 V
0 ms
0 ms
3.7 ms
3.7 ms
7.4 ms
7.4 ms
10.7 ms
10.7 ms
T
T
2.0 A
2.0 A
Voltage
Voltage
Input
Current
Input
Current
3.9 V
3.9 V
