Monitor The Power Supply; Turn On And Off Scenarios; Turn On Module Using The Pwrkey - Quectel EC21 Series Hardware Design

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.
PWRKEY 21
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.
≥100ms
Turn on pulse
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.
EC21_Hardware_Design
Description
Turn on/off the module
4.7K
Figure 10: Turn on the Module Using Driving Circuit
DC Characteristics
V max=2.1V
IH
V min=1.3V
IH
V max=0.5V
IL
47K
Confidential / Released
LTE Module Series
EC21 Hardware Design
Comment
The output voltage is 0.8V
because of the diode drop in
the Qualcomm chipset.
PWRKEY
35 / 94