LTE Module Series
EG21-G Hardware Design
EG21-G_Hardware_Design 34 / 100
3.7.
Power-on and off Scenarios
3.7.1.
Turn on Module Using the PWRKEY
The following table shows the pin definition of PWRKEY.
Table 7: Pin Definition of PWRKEY
Pin Name
Pin No.
I/O
Description
Comment
PWRKEY
21
DI
Turn on/off the module
The output voltage is 0.8V
because of the diode drop in
the Qualcomm chipset.
When EG21-G is in power-down mode, it can be turned on to normal mode by driving the PWRKEY pin to
a low level for at least 500ms. It is recommended to use an open drain/collector driver to control the
PWRKEY. After STATUS pin (require external pull-up) outputs a low level, PWRKEY pin can be released.
A simple reference circuit is illustrated in the following figure.
Turn on pulse
PWRKEY
4.7K
47K
≥ 500ms
10nF
Figure 10: Turn on the Module by Using Driving Circuit
The other way to control the PWRKEY is using a button directly. When pressing the key, electrostatic
strike may generate from finger. Therefore, a TVS component is indispensable to be placed nearby the
button for ESD protection. A reference circuit is shown in the following figure.
PWRKEY
S1
Close to S1
TVS