N1_Hardware_User_Guide
Copyright © Neoway Technology Co., Ltd
18
Figure 3-2
Reference design of power supply control
VCC_IN_5V
VBAT
100 uF
TAN
0.1 uF
TVS
5V
10 uF
470uF
TAN
10K
4.75K
VOUT
MIC29302WU
EN
VIN
ADJ
0.1 uF 100pF 33pF
PWR_EN
The alternative way is to use an enhancement mode p-MOSFET to control the module's power, as shown
in Figure 3-3. When the external MCU detects the exceptions such as no response from the module or the
disconnection of GPRS, power off/on can rectify the module exceptions.
In Figure 3-3, the module is turned on when PWR_EN is set to high level.
Figure 3-3
Reference design of power supply controlled by p-MOSFET
VCC_IN_3.9V
VBAT
10K
100K
33 pF
10 uF
2K
10K
0.1 uF
Q1
R4
C1
C2
C4
C5
C7
R1
R2
10 uF 0.1 uF
R3
Q2
TVS
5V
470 uF
C3
C6
100pF
S
G
D
PWR_EN
Q2 is added to eliminate the need for a high voltage level of the host GPIO. In case that the GPIO can
output a high voltage greater than VCCIN - |VGS(th)|, where VGS(th) is the Gate Threshold Voltage, Q2
is not needed.
Reference components:
Q1 can be IRML6401 or low Rds(on) pMOSFET which has an ability to withstand higher voltage
and drain current.
