Neo_M660A 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
Pin Name
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, 2 mA at most
ON/OFF
DI
ON/OFF input
Triggered by low level
RESET
DI
Module reset input
Triggered by low level
Keep more than 100 ms
3.1.1 VBAT
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 VBAT 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. If the voltage drops lower than 3.5 V, the
module might restart.
Figure 3-1
Current peaks and voltage drops
Keep above 3.5 V
3.5 V
0 ms
3.7 ms
7.4 ms
10.7 ms
T
2 A
Voltage
Input
current
3.9 V
