![Quectel EC21 Series Скачать руководство пользователя страница 36](http://html2.mh-extra.com/html/quectel/ec21-series/ec21-series_hardware-design_3601488036.webp)
LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design Confidential / Released 35 / 94
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. Turn on and off Scenarios
3.7.1. Turn on Module Using the PWRKEY
The following table shows the pin definition of PWRKEY.
Table 7: PWRKEY Pin Description
Pin Name Pin No.
Description
DC Characteristics Comment
PWRKEY
21
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 EC21 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 100ms. It is recommended to use an open drain/collector driver to control the
PWRKEY. After STATUS pin (require external pull-up) outputting 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
≥100ms
Figure 10: Turn on the Module 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.
Quectel
Confidential