Product Info

LTE Module Series
EG91 Hardware Design
EG91_Hardware_Design 37 / 93
3.6.4. Monitor the Power Supply
AT+CBC command can be used to monitor the VBAT_BB voltage value. For more details, please refer to
document [2].
3.7. Power-on/off Scenarios
3.7.1. Turn on Module Using the PWRKEY
The following table shows the pin definitionof PWRKEY.
Table 7: Pin Definition of PWRKEY
Pin Name Pin No. Description DC Characteristics Comment
PWRKEY 15 Turn on/off the module
V
IH
max=2.1V
V
IH
min=1.3V
V
IL
max=0.5V
The output voltage is 0.8V
because of the diode drop in
the Qualcomm chipset.
When EG91 is in powerdown 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 outputting a high level, PWRKEY pin can be released. A simple reference
circuit is illustrated in the following figure.
Figure 10: Turn on the Module Using Driving Circuit
Another way to control the PWRKEY is using a button directly. When pressing the key, electrostatic strike
may generate from the finger. Therefore, aTVS component is indispensable to be placed nearby the
button for ESD protection. A reference circuit is shownin the following figure.